Adds human readable descriptions to build configs (#51929)

Step 4 of https://github.com/flutter/flutter/issues/145263

Hopefully these descriptions will be more useful than the list of GN
args.
diff --git a/ci/builders/linux_android_aot_engine.json b/ci/builders/linux_android_aot_engine.json
index 116e0fc..41dfccb 100644
--- a/ci/builders/linux_android_aot_engine.json
+++ b/ci/builders/linux_android_aot_engine.json
@@ -34,6 +34,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_profile",
+            "description": "Produces profile mode artifacts to target 32-bit arm Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_profile",
                 "targets": [
@@ -78,6 +79,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_release",
+            "description": "Produces release mode artifacts to target 32-bit arm Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_release",
                 "targets": [
@@ -123,6 +125,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_release_arm64",
+            "description": "Produces release mode artifacts to target 64-bit arm Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_release_arm64",
                 "targets": [
@@ -179,6 +182,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_profile_arm64",
+            "description": "Produces profile mode artifacts to target 64-bit arm Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_profile_arm64",
                 "targets": [
@@ -241,6 +245,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_profile_x64",
+            "description": "Produces profile mode artifacts to target x64 Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_profile_x64",
                 "targets": [
@@ -286,6 +291,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_release_x64",
+            "description": "Produces release mode artifacts to target x64 Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_release_x64",
                 "targets": [
diff --git a/ci/builders/linux_android_debug_engine.json b/ci/builders/linux_android_debug_engine.json
index c35c7fc..8c7c517 100644
--- a/ci/builders/linux_android_debug_engine.json
+++ b/ci/builders/linux_android_debug_engine.json
@@ -30,6 +30,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_jit_release_x86",
+            "description": "Produces jit-release mode artifacts to target x86 Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_jit_release_x86",
                 "targets": [
@@ -89,6 +90,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug",
+            "description": "Produces debug mode artifacts to target 32-bit arm Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_debug",
                 "targets": [
@@ -147,6 +149,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug_arm64",
+            "description": "Produces debug mode artifacts to target 64-bit arm Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_debug_arm64",
                 "targets": [
@@ -186,6 +189,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug_x86",
+            "description": "Produces debug mode artifacts to target x86 Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_debug_x86",
                 "targets": [
@@ -225,6 +229,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug_x64",
+            "description": "Produces debug mode artifacts to target x64 Android from a Linux host.",
             "ninja": {
                 "config": "ci/android_debug_x64",
                 "targets": [
diff --git a/ci/builders/linux_android_emulator.json b/ci/builders/linux_android_emulator.json
index 4880c98..677915c 100644
--- a/ci/builders/linux_android_emulator.json
+++ b/ci/builders/linux_android_emulator.json
@@ -26,6 +26,7 @@
                 }
             ],
             "name": "ci/android_emulator_debug_x64",
+            "description": "Build for debug mode x64 Android emulator tests, and Impeller scenario app tests.",
             "ninja": {
                 "config": "ci/android_emulator_debug_x64",
                 "targets": [
@@ -118,6 +119,7 @@
                 }
             ],
             "name": "ci/android_emulator_debug_x86",
+            "description": "Build for debug mode x86 Android emulator tests.",
             "ninja": {
                 "config": "ci/android_emulator_debug_x86",
                 "targets": [
diff --git a/ci/builders/linux_android_emulator_skia.json b/ci/builders/linux_android_emulator_skia.json
index 4dbc933..e503550 100644
--- a/ci/builders/linux_android_emulator_skia.json
+++ b/ci/builders/linux_android_emulator_skia.json
@@ -26,6 +26,7 @@
                 }
             ],
             "name": "ci/android_emulator_skia_debug_x64",
+            "description": "Build for debug mode x64 Android Skia scenario app tests.",
             "ninja": {
                 "config": "ci/android_emulator_skia_debug_x64",
                 "targets": [
diff --git a/ci/builders/linux_arm_host_engine.json b/ci/builders/linux_arm_host_engine.json
index 937c6f5..289a8d2 100644
--- a/ci/builders/linux_arm_host_engine.json
+++ b/ci/builders/linux_arm_host_engine.json
@@ -33,6 +33,7 @@
                 "--no-goma"
             ],
             "name": "ci/linux_profile_arm64",
+            "description": "Produces profile mode artifacts to target arm64 Linux from a Linux host.",
             "ninja": {
                 "config": "ci/linux_profile_arm64",
                 "targets": [
@@ -75,6 +76,7 @@
                 "--no-goma"
             ],
             "name": "ci/linux_debug_arm64",
+            "description": "Produces debug mode artifacts to target arm64 Linux from a Linux host.",
             "ninja": {
                 "config": "ci/linux_debug_arm64",
                 "targets": [
@@ -117,6 +119,7 @@
                 "--no-goma"
             ],
             "name": "ci/linux_release_arm64",
+            "description": "Produces release mode artifacts to target arm64 Linux from a Linux host.",
             "ninja": {
                 "config": "ci/linux_release_arm64",
                 "targets": [
diff --git a/ci/builders/linux_clang_tidy.json b/ci/builders/linux_clang_tidy.json
index 0d81a7b..a980346 100644
--- a/ci/builders/linux_clang_tidy.json
+++ b/ci/builders/linux_clang_tidy.json
@@ -20,6 +20,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug_arm64_clang_tidy",
+            "description": "A debug mode arm64 Android build used only as the basis for a clang-tidy run.",
             "ninja": {
                 "config": "ci/android_debug_arm64_clang_tidy"
             }
@@ -44,6 +45,7 @@
                 "--no-goma"
             ],
             "name": "ci/host_debug_clang_tidy",
+            "description": "A debug mode Linux host build used only as the basis for a clang-tidy run.",
             "ninja": {
                 "config": "ci/host_debug_clang_tidy"
             }
diff --git a/ci/builders/linux_fuchsia.json b/ci/builders/linux_fuchsia.json
index 6212ee2..271bcf4 100644
--- a/ci/builders/linux_fuchsia.json
+++ b/ci/builders/linux_fuchsia.json
@@ -21,6 +21,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_profile_arm64",
+            "description": "Produces profile mode artifacts to target arm64 Fuchsia from a Linux host.",
             "ninja": {
                 "config": "ci/fuchsia_profile_arm64",
                 "targets": [
@@ -53,6 +54,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_profile_arm64_tester",
+            "description": "Builds profile mode tests of arm64 Fuchsia.",
             "ninja": {
                 "config": "ci/fuchsia_profile_arm64_tester",
                 "targets": [
@@ -94,6 +96,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_release_arm64",
+            "description": "Produces release mode artifacts to target arm64 Fuchsia from a Linux host.",
             "ninja": {
                 "config": "ci/fuchsia_release_arm64",
                 "targets": [
@@ -126,6 +129,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_release_arm64_tester",
+            "description": "Builds release mode tests of arm64 Fuchsia.",
             "ninja": {
                 "config": "ci/fuchsia_release_arm64_tester",
                 "targets": [
@@ -168,6 +172,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_debug_arm64",
+            "description": "Produces debug mode artifacts to target arm64 Fuchsia from a Linux host.",
             "ninja": {
                 "config": "ci/fuchsia_debug_arm64",
                 "targets": [
@@ -215,6 +220,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_debug_arm64_tester",
+            "description": "Builds debug mode tests of arm64 Fuchsia.",
             "ninja": {
                 "config": "ci/fuchsia_debug_arm64_tester",
                 "targets": [
@@ -256,6 +262,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_profile_x64",
+            "description": "Produces profile mode artifacts to target x64 Fuchsia from a Linux host.",
             "ninja": {
                 "config": "ci/fuchsia_profile_x64",
                 "targets": [
@@ -288,6 +295,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_profile_x64_tester",
+            "description": "Builds profile mode tests of x64 Fuchsia.",
             "ninja": {
                 "config": "ci/fuchsia_profile_x64_tester",
                 "targets": [
@@ -330,6 +338,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_release_x64",
+            "description": "Produces release mode artifacts to target x64 Fuchsia from a Linux host.",
             "ninja": {
                 "config": "ci/fuchsia_release_x64",
                 "targets": [
@@ -362,6 +371,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_release_x64_tester",
+            "description": "Builds release mode tests of x64 Fuchsia.",
             "ninja": {
                 "config": "ci/fuchsia_release_x64_tester",
                 "targets": [
@@ -405,6 +415,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_debug_x64",
+            "description": "Produces debug mode artifacts to target x64 Fuchsia from a Linux host.",
             "ninja": {
                 "config": "ci/fuchsia_debug_x64",
                 "targets": [
@@ -452,6 +463,7 @@
                 "--no-goma"
             ],
             "name": "ci/fuchsia_debug_x64_tester",
+            "description": "Builds debug mode tests of x64 Fuchsia.",
             "ninja": {
                 "config": "ci/fuchsia_debug_x64_tester",
                 "targets": [
diff --git a/ci/builders/linux_host_desktop_engine.json b/ci/builders/linux_host_desktop_engine.json
index 773deb9..c0d05b3 100644
--- a/ci/builders/linux_host_desktop_engine.json
+++ b/ci/builders/linux_host_desktop_engine.json
@@ -31,6 +31,7 @@
                 "ci/host_debug_desktop"
             ],
             "name": "ci/host_debug_desktop",
+            "description": "Produces debug mode artifacts for x64 Linux desktop.",
             "ninja": {
                 "config": "ci/host_debug_desktop",
                 "targets": [
@@ -70,6 +71,7 @@
                 "ci/host_profile_desktop"
             ],
             "name": "ci/host_profile_desktop",
+            "description": "Produces profile mode artifacts for x64 Linux desktop.",
             "ninja": {
                 "config": "ci/host_profile_desktop",
                 "targets": [
@@ -108,6 +110,7 @@
                 "ci/host_release_desktop"
             ],
             "name": "ci/host_release_desktop",
+            "description": "Produces release mode artifacts for x64 Linux desktop.",
             "ninja": {
                 "config": "ci/host_release_desktop",
                 "targets": [
diff --git a/ci/builders/linux_host_engine.json b/ci/builders/linux_host_engine.json
index 904dbaa..e89a80f 100644
--- a/ci/builders/linux_host_engine.json
+++ b/ci/builders/linux_host_engine.json
@@ -35,6 +35,7 @@
                 "--no-goma"
             ],
             "name": "ci/host_debug",
+            "description": "Produces debug mode Linux host-side tooling and builds host-side unit tests for Linux.",
             "ninja": {
                 "config": "ci/host_debug",
                 "targets": [
@@ -91,6 +92,7 @@
                 "--no-goma"
             ],
             "name": "ci/host_profile",
+            "description": "Produces profile mode Linux host-side tooling and builds host-side unit tests for Linux.",
             "ninja": {
                 "config": "ci/host_profile",
                 "targets": [
@@ -152,6 +154,7 @@
                 "--no-goma"
             ],
             "name": "ci/host_release",
+            "description": "Produces release mode Linux host-side tooling and builds host-side unit tests and benchmarks for Linux.",
             "ninja": {
                 "config": "ci/host_release",
                 "targets": [
diff --git a/ci/builders/linux_unopt.json b/ci/builders/linux_unopt.json
index d80b870..f5f8b19 100644
--- a/ci/builders/linux_unopt.json
+++ b/ci/builders/linux_unopt.json
@@ -23,6 +23,7 @@
                 "--no-goma"
             ],
             "name": "ci/host_debug_unopt",
+            "description": "Builds a debug mode unopt Linux engine. Builds and runs many tests and lints.",
             "ninja": {
                 "config": "ci/host_debug_unopt",
                 "targets": [
@@ -127,6 +128,7 @@
                 "--use-glfw-swiftshader"
             ],
             "name": "ci/host_debug_unopt_impeller_tests",
+            "description": "Builds a debug mode unopt Linux engine with swiftshader. Runs Impeller unit tests.",
             "ninja": {
                 "config": "ci/host_debug_unopt_impeller_tests",
                 "targets": [
@@ -169,6 +171,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_embedder_debug_unopt",
+            "description": "Builds embedder artifacts targeting 32-bit arm Android.",
             "ninja": {
                 "config": "ci/android_embedder_debug_unopt",
                 "targets": [
@@ -196,6 +199,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug_arm64_validation_layers",
+            "description": "Builds a debug mode engine targeting 64-bit arm Android with Vulkan validation layers.",
             "ninja": {
                 "config": "ci/android_debug_arm64_validation_layers",
                 "targets": [
@@ -227,6 +231,7 @@
                 "--no-goma"
             ],
             "name": "ci/android_debug_unopt",
+            "description": "Builds a debug mode unopt engine targeting 32-bit arm Android. Runs host-side Java unit tests and malioc.",
             "ninja": {
                 "config": "ci/android_debug_unopt",
                 "targets": [
diff --git a/ci/builders/linux_unopt_debug_no_rbe.json b/ci/builders/linux_unopt_debug_no_rbe.json
index f9c2009..19f2050 100644
--- a/ci/builders/linux_unopt_debug_no_rbe.json
+++ b/ci/builders/linux_unopt_debug_no_rbe.json
@@ -22,6 +22,7 @@
         "ci/linux_unopt_debug_no_rbe"
       ],
       "name": "ci/linux_unopt_debug_no_rbe",
+      "description": "Tests clangd on Linux.",
       "ninja": {
         "config": "ci/linux_unopt_debug_no_rbe",
         "targets": ["flutter/tools/font_subset"]
diff --git a/ci/builders/local_engine.json b/ci/builders/local_engine.json
index 2f0229e..679b566 100644
--- a/ci/builders/local_engine.json
+++ b/ci/builders/local_engine.json
@@ -21,6 +21,7 @@
         "--no-goma"
       ],
       "name": "macos/android_debug_arm64",
+      "description": "Builds a debug mode engine that targets 64-bit arm Android from a macOS host.",
       "ninja": {
         "config": "android_debug_arm64",
         "targets": []
@@ -51,6 +52,7 @@
         "--no-goma"
       ],
       "name": "linux/android_debug_arm64",
+      "description": "Builds a debug mode engine that targets 64-bit arm Android from a Linux host.",
       "ninja": {
         "config": "android_debug_arm64",
         "targets": []
@@ -76,6 +78,7 @@
         "--no-goma"
       ],
       "name": "windows/android_debug_arm64",
+      "description": "Builds a debug mode engine that targets 64-bit arm Android from a Windows host.",
       "ninja": {
         "config": "android_debug_arm64",
         "targets": []
@@ -103,6 +106,7 @@
         "--no-goma"
       ],
       "name": "macos/android_debug_unopt_arm64",
+      "description": "Builds a debug mode unopt engine that targets 64-bit arm Android from a macOS host.",
       "ninja": {
         "config": "android_debug_unopt_arm64",
         "targets": []
@@ -130,6 +134,7 @@
         "--no-goma"
       ],
       "name": "macos/android_profile_arm64",
+      "description": "Builds a profile mode engine that targets 64-bit arm Android from a macOS host.",
       "ninja": {
         "config": "android_profile_arm64",
         "targets": []
@@ -160,6 +165,7 @@
         "--no-goma"
       ],
       "name": "linux/android_profile_arm64",
+      "description": "Builds a profile mode engine that targets 64-bit arm Android from a Linux host.",
       "ninja": {
         "config": "android_profile_arm64",
         "targets": []
@@ -185,6 +191,7 @@
         "--no-goma"
       ],
       "name": "windows/android_profile_arm64",
+      "description": "Builds a profile mode engine that targets 64-bit arm Android from a Windows host.",
       "ninja": {
         "config": "android_profile_arm64",
         "targets": []
@@ -211,6 +218,7 @@
         "--no-goma"
       ],
       "name": "macos/android_release_arm64",
+      "description": "Builds a release mode engine that targets 64-bit arm Android from a macOS host.",
       "ninja": {
         "config": "android_release_arm64",
         "targets": []
@@ -241,6 +249,7 @@
         "--no-goma"
       ],
       "name": "linux/android_release_arm64",
+      "description": "Builds a release mode engine that targets 64-bit arm Android from a Linux host.",
       "ninja": {
         "config": "android_release_arm64",
         "targets": []
@@ -266,6 +275,7 @@
         "--no-goma"
       ],
       "name": "windows/android_release_arm64",
+      "description": "Builds a release mode engine that targets 64-bit arm Android from a Windows host.",
       "ninja": {
         "config": "android_release_arm64",
         "targets": []
@@ -291,6 +301,7 @@
         "--no-goma"
       ],
       "name": "macos/host_debug",
+      "description": "Builds a debug mode engine for a macOS host.",
       "ninja": {
         "config": "host_debug",
         "targets": []
@@ -320,6 +331,7 @@
         "--no-goma"
       ],
       "name": "linux/host_debug",
+      "description": "Builds a debug mode engine for a Linux host.",
       "ninja": {
         "config": "host_debug",
         "targets": []
@@ -344,6 +356,7 @@
         "--no-goma"
       ],
       "name": "windows/host_debug",
+      "description": "Builds a debug mode engine for a Windows host.",
       "ninja": {
         "config": "host_debug",
         "targets": []
@@ -369,6 +382,7 @@
         "--no-goma"
       ],
       "name": "macos/host_profile",
+      "description": "Builds a profile mode engine for a macOS host.",
       "ninja": {
         "config": "host_profile",
         "targets": []
@@ -398,6 +412,7 @@
         "--no-goma"
       ],
       "name": "linux/host_profile",
+      "description": "Builds a profile mode engine for a Linux host.",
       "ninja": {
         "config": "host_profile",
         "targets": []
@@ -422,6 +437,7 @@
         "--no-goma"
       ],
       "name": "windows/host_profile",
+      "description": "Builds a profile mode engine for a Windows host.",
       "ninja": {
         "config": "host_profile",
         "targets": []
@@ -447,6 +463,7 @@
         "--no-goma"
       ],
       "name": "macos/host_release",
+      "description": "Builds a release mode engine for a macOS host.",
       "ninja": {
         "config": "host_release",
         "targets": []
@@ -477,6 +494,7 @@
         "--xcode-symlinks"
       ],
       "name": "linux/host_release",
+      "description": "Builds a release mode engine for a Linux host.",
       "ninja": {
         "config": "host_release",
         "targets": []
@@ -502,6 +520,7 @@
         "--xcode-symlinks"
       ],
       "name": "windows/host_release",
+      "description": "Builds a release mode engine for a Windows host.",
       "ninja": {
         "config": "host_release",
         "targets": []
diff --git a/ci/builders/mac_android_aot_engine.json b/ci/builders/mac_android_aot_engine.json
index 58463ae..0651125 100644
--- a/ci/builders/mac_android_aot_engine.json
+++ b/ci/builders/mac_android_aot_engine.json
@@ -28,6 +28,7 @@
                 "--android"
             ],
             "name": "ci/android_profile",
+            "description": "Produces profile mode artifacts to target 32-bit arm Android from a macOS host.",
             "ninja": {
                 "config": "ci/android_profile",
                 "targets": [
@@ -70,6 +71,7 @@
                 "--android-cpu=arm64"
             ],
             "name": "ci/android_profile_arm64",
+            "description": "Produces profile mode artifacts to target 64-bit arm Android from a macOS host.",
             "ninja": {
                 "config": "ci/android_profile_arm64",
                 "targets": [
@@ -112,6 +114,7 @@
                 "--android-cpu=x64"
             ],
             "name": "ci/android_profile_x64",
+            "description": "Produces profile mode artifacts to target x64 Android from a macOS host.",
             "ninja": {
                 "config": "ci/android_profile_x64",
                 "targets": [
@@ -153,6 +156,7 @@
                 "--android"
             ],
             "name": "ci/android_release",
+            "description": "Produces release mode artifacts to target 32-bit arm Android from a macOS host.",
             "ninja": {
                 "config": "ci/android_release",
                 "targets": [
@@ -195,6 +199,7 @@
                 "--android-cpu=arm64"
             ],
             "name": "ci/android_release_arm64",
+            "description": "Produces release mode artifacts to target 64-bit arm Android from a macOS host.",
             "ninja": {
                 "config": "ci/android_release_arm64",
                 "targets": [
@@ -237,6 +242,7 @@
                 "--android-cpu=x64"
             ],
             "name": "ci/android_release_x64",
+            "description": "Produces release mode artifacts to target x64 Android from a macOS host.",
             "ninja": {
                 "config": "ci/android_release_x64",
                 "targets": [
diff --git a/ci/builders/mac_clang_tidy.json b/ci/builders/mac_clang_tidy.json
index 789ee39..2b9a3aa 100644
--- a/ci/builders/mac_clang_tidy.json
+++ b/ci/builders/mac_clang_tidy.json
@@ -23,6 +23,7 @@
                 "--xcode-symlinks"
             ],
             "name": "ci/host_debug_clang_tidy",
+            "description": "A debug mode macOS host build used only as the basis for a clang-tidy run.",
             "ninja": {
                 "config": "ci/host_debug_clang_tidy"
             }
@@ -51,6 +52,7 @@
                 "--xcode-symlinks"
             ],
             "name": "ci/ios_debug_sim_clang_tidy",
+            "description": "A debug mode iOS simulator build used only as the basis for a clang-tidy run.",
             "ninja": {
                 "config": "ci/ios_debug_sim_clang_tidy"
             }
diff --git a/ci/builders/mac_host_engine.json b/ci/builders/mac_host_engine.json
index 7d116dd..1a9e8a2 100644
--- a/ci/builders/mac_host_engine.json
+++ b/ci/builders/mac_host_engine.json
@@ -33,6 +33,7 @@
                 "--use-glfw-swiftshader"
             ],
             "name": "ci/host_debug",
+            "description": "Produces debug mode x64 macOS host-side tooling and builds host-side unit tests for x64 macOS.",
             "ninja": {
                 "config": "ci/host_debug",
                 "targets": [
@@ -97,6 +98,7 @@
                 "--build-embedder-examples"
             ],
             "name": "ci/host_profile",
+            "description": "Produces profile mode x64 macOS host-side tooling and builds host-side unit tests for x64 macOS.",
             "ninja": {
                 "config": "ci/host_profile",
                 "targets": [
@@ -166,6 +168,7 @@
                 "--use-glfw-swiftshader"
             ],
             "name": "ci/host_release",
+            "description": "Produces release mode x64 macOS host-side tooling and builds host-side unit tests for x64 macOS.",
             "ninja": {
                 "config": "ci/host_release",
                 "targets": [
@@ -230,6 +233,7 @@
                 "--prebuilt-dart-sdk"
             ],
             "name": "ci/mac_debug_arm64",
+            "description": "Produces debug mode arm64 macOS host-side tooling.",
             "ninja": {
                 "config": "ci/mac_debug_arm64",
                 "targets": [
@@ -279,6 +283,7 @@
                 "--prebuilt-dart-sdk"
             ],
             "name": "ci/mac_profile_arm64",
+            "description": "Produces profile mode arm64 macOS host-side tooling.",
             "ninja": {
                 "config": "ci/mac_profile_arm64",
                 "targets": [
@@ -325,6 +330,7 @@
                 "--prebuilt-dart-sdk"
             ],
             "name": "ci/mac_release_arm64",
+            "description": "Produces release mode arm64 macOS host-side tooling.",
             "ninja": {
                 "config": "ci/mac_release_arm64",
                 "targets": [
diff --git a/ci/builders/mac_impeller_cmake_example.json b/ci/builders/mac_impeller_cmake_example.json
index 9bc57f2..3420bab 100644
--- a/ci/builders/mac_impeller_cmake_example.json
+++ b/ci/builders/mac_impeller_cmake_example.json
@@ -3,6 +3,7 @@
         {
             "cas_archive": false,
             "name": "ci/impeller-cmake-example",
+            "description": "Builds the Impeller cmake example.",
             "archives": [],
             "drone_dimensions": [
                 "device_type=none",
diff --git a/ci/builders/mac_ios_engine.json b/ci/builders/mac_ios_engine.json
index 013a0c5..368862d 100644
--- a/ci/builders/mac_ios_engine.json
+++ b/ci/builders/mac_ios_engine.json
@@ -16,6 +16,7 @@
                 "--no-lto"
             ],
             "name": "ci/ios_debug_sim",
+            "description": "Produces debug mode artifacts to target the x64 iOS simulator.",
             "ninja": {
                 "config": "ci/ios_debug_sim"
             },
@@ -41,6 +42,7 @@
                 "--no-lto"
             ],
             "name": "ci/ios_debug_sim_arm64",
+            "description": "Produces debug mode artifacts to target the arm64 iOS simulator.",
             "ninja": {
                 "config": "ci/ios_debug_sim_arm64"
             },
@@ -63,6 +65,7 @@
                 "debug"
             ],
             "name": "ci/ios_debug",
+            "description": "Produces debug mode artifacts to target iOS.",
             "ninja": {
                 "config": "ci/ios_debug",
                 "targets": [
@@ -88,6 +91,7 @@
                 "profile"
             ],
             "name": "ci/ios_profile",
+            "description": "Produces profile mode artifacts to target iOS.",
             "ninja": {
                 "config": "ci/ios_profile",
                 "targets": [
@@ -114,6 +118,7 @@
                 "release"
             ],
             "name": "ci/ios_release",
+            "description": "Produces release mode artifacts to target iOS.",
             "ninja": {
                 "config": "ci/ios_release",
                 "targets": [
@@ -144,6 +149,7 @@
                 "--darwin-extension-safe"
             ],
             "name": "ci/ios_debug_sim_extension_safe",
+            "description": "Produces extension safe debug mode artifacts to target the x64 iOS simulator.",
             "ninja": {
                 "config": "ci/ios_debug_sim_extension_safe"
             },
@@ -170,6 +176,7 @@
                 "--darwin-extension-safe"
             ],
             "name": "ci/ios_debug_sim_arm64_extension_safe",
+            "description": "Produces extension safe debug mode artifacts to target the arm64 iOS simulator.",
             "ninja": {
                 "config": "ci/ios_debug_sim_arm64_extension_safe"
             },
@@ -193,6 +200,7 @@
                 "--darwin-extension-safe"
             ],
             "name": "ci/ios_debug_extension_safe",
+            "description": "Produces extension safe debug mode artifacts to target iOS.",
             "ninja": {
                 "config": "ci/ios_debug_extension_safe",
                 "targets": [
@@ -219,6 +227,7 @@
                 "--darwin-extension-safe"
             ],
             "name": "ci/ios_profile_extension_safe",
+            "description": "Produces extension safe profile mode artifacts to target iOS.",
             "ninja": {
                 "config": "ci/ios_profile_extension_safe",
                 "targets": [
@@ -246,6 +255,7 @@
                 "--darwin-extension-safe"
             ],
             "name": "ci/ios_release_extension_safe",
+            "description": "Produces extension safe release mode artifacts to target iOS.",
             "ninja": {
                 "config": "ci/ios_release_extension_safe",
                 "targets": [
diff --git a/ci/builders/mac_unopt.json b/ci/builders/mac_unopt.json
index e7acb1e..d9957b9 100644
--- a/ci/builders/mac_unopt.json
+++ b/ci/builders/mac_unopt.json
@@ -25,6 +25,7 @@
                 "--xcode-symlinks"
             ],
             "name": "ci/host_debug_unopt",
+            "description": "Builds a debug mode unopt x64 macOS engine and runs host-side tests.",
             "ninja": {
                 "config": "ci/host_debug_unopt",
                 "targets": []
@@ -85,6 +86,7 @@
                 "ci/ios_debug_unopt_sim"
             ],
             "name": "ci/ios_debug_unopt_sim",
+            "description": "Builds a debug mode engine for x64 iOS simulator. Runs unit tests and the scenario app tests.",
             "ninja": {
                 "config": "ci/ios_debug_unopt_sim",
                 "targets": [
@@ -143,6 +145,7 @@
                 "--use-glfw-swiftshader"
             ],
             "name": "ci/host_debug_unopt_arm64",
+            "description": "Builds a debug mode unopt arm64 macOS engine and runs host-side tests.",
             "ninja": {
                 "config": "ci/host_debug_unopt_arm64",
                 "targets": [
@@ -202,6 +205,7 @@
                 "ci/ios_debug_unopt_sim_arm64"
             ],
             "name": "ci/ios_debug_unopt_sim_arm64",
+            "description": "Builds a debug mode engine for arm64 iOS simulator. Runs unit tests and the scenario app tests.",
             "ninja": {
                 "config": "ci/ios_debug_unopt_sim_arm64",
                 "targets": [
@@ -269,6 +273,7 @@
                 "ci/ios_debug_unopt_sim_arm64_extension_safe"
             ],
             "name": "ci/ios_debug_unopt_sim_arm64_extension_safe",
+            "description": "Builds an extension safe debug mode engine for arm64 iOS simulator. Runs unit tests and the scenario app tests.",
             "ninja": {
                 "config": "ci/ios_debug_unopt_sim_arm64_extension_safe",
                 "targets": [
diff --git a/ci/builders/mac_unopt_debug_no_rbe.json b/ci/builders/mac_unopt_debug_no_rbe.json
index 7287e89..a4bfc7e 100644
--- a/ci/builders/mac_unopt_debug_no_rbe.json
+++ b/ci/builders/mac_unopt_debug_no_rbe.json
@@ -28,6 +28,7 @@
         "ci/mac_unopt_debug_no_rbe"
       ],
       "name": "ci/mac_unopt_debug_no_rbe",
+      "description": "Tests clangd on macOS.",
       "ninja": {
         "config": "ci/mac_unopt_debug_no_rbe",
         "targets": ["flutter/tools/font_subset"]
diff --git a/ci/builders/standalone/linux_benchmarks.json b/ci/builders/standalone/linux_benchmarks.json
index 36ebfc4..45a074a 100644
--- a/ci/builders/standalone/linux_benchmarks.json
+++ b/ci/builders/standalone/linux_benchmarks.json
@@ -18,6 +18,7 @@
         "--no-goma"
     ],
     "name": "ci/host_release_benchmarks",
+    "description": "Builds and runs host-side benchmarks on Linux.",
     "ninja": {
         "config": "ci/host_release_benchmarks",
         "targets": [
diff --git a/ci/builders/standalone/linux_license.json b/ci/builders/standalone/linux_license.json
index 3013e3c..8c5bb2c 100644
--- a/ci/builders/standalone/linux_license.json
+++ b/ci/builders/standalone/linux_license.json
@@ -5,6 +5,7 @@
     ],
     "cas_archive": false,
     "name": "licenses",
+    "description": "Runs the license check script.",
     "tests": [
         {
             "name": "licenses check",
diff --git a/ci/builders/standalone/windows_unopt.json b/ci/builders/standalone/windows_unopt.json
index 317d7ec..1d6cce4 100644
--- a/ci/builders/standalone/windows_unopt.json
+++ b/ci/builders/standalone/windows_unopt.json
@@ -24,6 +24,7 @@
         "--no-goma"
     ],
     "name": "ci\\host_debug_unopt",
+    "description": "Builds a debug mode unopt engine for Windows and runs unit tests.",
     "ninja": {
         "config": "ci/host_debug_unopt"
     },
diff --git a/ci/builders/windows_android_aot_engine.json b/ci/builders/windows_android_aot_engine.json
index b1bc13d..2e28455 100644
--- a/ci/builders/windows_android_aot_engine.json
+++ b/ci/builders/windows_android_aot_engine.json
@@ -29,6 +29,7 @@
                 "--rbe"
             ],
             "name": "ci\\android_profile",
+            "description": "Produces profile mode artifacts to target 32-bit arm Android from a Windows host.",
             "ninja": {
                 "config": "ci/android_profile",
                 "targets": [
@@ -66,6 +67,7 @@
                 "--rbe"
             ],
             "name": "ci\\android_profile_arm64",
+            "description": "Produces profile mode artifacts to target 64-bit arm Android from a Windows host.",
             "ninja": {
                 "config": "ci/android_profile_arm64",
                 "targets": [
@@ -103,6 +105,7 @@
                 "--rbe"
             ],
             "name": "ci\\android_profile_x64",
+            "description": "Produces profile mode artifacts to target x64 Android from a Windows host.",
             "ninja": {
                 "config": "ci/android_profile_x64",
                 "targets": [
@@ -139,6 +142,7 @@
                 "--rbe"
             ],
             "name": "ci\\android_release",
+            "description": "Produces release mode artifacts to target 32-bit arm Android from a Windows host.",
             "ninja": {
                 "config": "ci/android_release",
                 "targets": [
@@ -176,6 +180,7 @@
                 "--rbe"
             ],
             "name": "ci\\android_release_arm64",
+            "description": "Produces release mode artifacts to target 64-bit arm Android from a Windows host.",
             "ninja": {
                 "config": "ci/android_release_arm64",
                 "targets": [
@@ -213,6 +218,7 @@
                 "--rbe"
             ],
             "name": "ci\\android_release_x64",
+            "description": "Produces release mode artifacts to target x64 Android from a Windows host.",
             "ninja": {
                 "config": "ci/android_release_x64",
                 "targets": [
diff --git a/ci/builders/windows_arm_host_engine.json b/ci/builders/windows_arm_host_engine.json
index e2f316e..d4d8d96 100644
--- a/ci/builders/windows_arm_host_engine.json
+++ b/ci/builders/windows_arm_host_engine.json
@@ -37,6 +37,7 @@
                 "--rbe"
             ],
             "name": "ci\\host_debug_arm64",
+            "description": "Produces debug mode artifacts to target arm64 Windows from an x64 Windows host.",
             "ninja": {
                 "config": "ci/host_debug_arm64",
                 "targets": [
@@ -81,6 +82,7 @@
                 "--rbe"
             ],
             "name": "ci\\host_profile_arm64",
+            "description": "Produces profile mode artifacts to target arm64 Windows from an x64 Windows host.",
             "ninja": {
                 "config": "ci/host_profile_arm64",
                 "targets": [
@@ -123,6 +125,7 @@
                 "--rbe"
             ],
             "name": "ci\\host_release_arm64",
+            "description": "Produces release mode artifacts to target arm64 Windows from an x64 Windows host.",
             "ninja": {
                 "config": "ci/host_release_arm64",
                 "targets": [
diff --git a/ci/builders/windows_host_engine.json b/ci/builders/windows_host_engine.json
index a8f1f99..362f430 100644
--- a/ci/builders/windows_host_engine.json
+++ b/ci/builders/windows_host_engine.json
@@ -35,6 +35,7 @@
                 "--rbe"
             ],
             "name": "ci\\host_debug",
+            "description": "Produces debug mode Windows host-side tooling and builds host-side unit tests for Windows.",
             "ninja": {
                 "config": "ci/host_debug",
                 "targets": [
@@ -91,6 +92,7 @@
                 "--rbe"
             ],
             "name": "ci\\host_profile",
+            "description": "Produces profile mode Windows host-side tooling.",
             "ninja": {
                 "config": "ci/host_profile",
                 "targets": [
@@ -131,6 +133,7 @@
                 "--rbe"
             ],
             "name": "ci\\host_release",
+            "description": "Produces release mode Windows host-side tooling.",
             "ninja": {
                 "config": "ci/host_release",
                 "targets": [
diff --git a/tools/engine_tool/lib/src/commands/command.dart b/tools/engine_tool/lib/src/commands/command.dart
index 0ef132d..5b9ea0a 100644
--- a/tools/engine_tool/lib/src/commands/command.dart
+++ b/tools/engine_tool/lib/src/commands/command.dart
@@ -37,7 +37,7 @@
     ],
     allowedHelp: <String, String>{
       for (final Build config in builds)
-        mangleConfigName(environment, config.name): config.gn.join(' '),
+        mangleConfigName(environment, config.name): config.description,
     },
   );
 }
diff --git a/tools/pkg/engine_build_configs/lib/src/build_config.dart b/tools/pkg/engine_build_configs/lib/src/build_config.dart
index 6718f63..97db846 100644
--- a/tools/pkg/engine_build_configs/lib/src/build_config.dart
+++ b/tools/pkg/engine_build_configs/lib/src/build_config.dart
@@ -174,6 +174,7 @@
 /// "builds" contains a list of maps with fields like:
 /// {
 ///   "name": "",
+///   "description": "",
 ///   "gn": [""],
 ///   "ninja": {},
 ///   "tests": [],
@@ -188,6 +189,7 @@
   factory Build.fromJson(Map<String, Object?> map) {
     final List<String> errors = <String>[];
     final String? name = stringOfJson(map, 'name', errors);
+    final String? description = stringOfJson(map, 'description', errors);
     final List<String>? gn = stringListOfJson(map, 'gn', errors);
     final List<BuildTest>? tests = objListOfJson(
       map,
@@ -247,6 +249,7 @@
     }
 
     if (name == null ||
+        description == null ||
         gn == null ||
         ninja == null ||
         archives == null ||
@@ -258,6 +261,7 @@
     }
     return Build._(
       name,
+      description,
       gn,
       ninja,
       tests,
@@ -270,6 +274,7 @@
 
   Build._(
     this.name,
+    this.description,
     this.gn,
     this.ninja,
     this.tests,
@@ -281,6 +286,7 @@
 
   Build._invalid(super.errors)
       : name = '',
+        description = '',
         gn = <String>[],
         ninja = BuildNinja.nop(),
         tests = <BuildTest>[],
@@ -293,6 +299,9 @@
   /// depdendency of a global test.
   final String name;
 
+  /// The human-readable description of what a build accomplishes.
+  final String description;
+
   /// The parameters to pass to `flutter/tools/gn` to configure the build.
   final List<String> gn;
 
diff --git a/tools/pkg/engine_build_configs/test/build_config_test.dart b/tools/pkg/engine_build_configs/test/build_config_test.dart
index d1685f0..167e716 100644
--- a/tools/pkg/engine_build_configs/test/build_config_test.dart
+++ b/tools/pkg/engine_build_configs/test/build_config_test.dart
@@ -22,6 +22,7 @@
 
     final Build globalBuild = buildConfig.builds[0];
     expect(globalBuild.name, equals('build_name'));
+    expect(globalBuild.description, equals('build_description'));
     expect(globalBuild.gn.length, equals(4));
     expect(globalBuild.gn[0], equals('--gn-arg'));
     expect(globalBuild.droneDimensions.length, equals(1));
diff --git a/tools/pkg/engine_build_configs/test/fixtures.dart b/tools/pkg/engine_build_configs/test/fixtures.dart
index f168a40..bc3b448 100644
--- a/tools/pkg/engine_build_configs/test/fixtures.dart
+++ b/tools/pkg/engine_build_configs/test/fixtures.dart
@@ -23,6 +23,7 @@
       },
       "gn": ["--gn-arg", "--lto", "--goma", "--no-rbe"],
       "name": "build_name",
+      "description": "build_description",
       "ninja": {
         "config": "build_name",
         "targets": ["ninja_target"]