| [](https://pub.dev/packages/dart_mcp) |
| [](https://pub.dev/packages/dart_mcp/publisher) |
| |
| A Dart package for making MCP servers and clients. |
| |
| **Note**: This package is still experimental and is likely to evolve quickly. |
| |
| ## Implementing Servers |
| |
| To implement a server, import `package:dart_mcp/server.dart` and extend the |
| `MCPServer` class. You must provide the server a communication channel to send |
| and receive messages with. |
| |
| For each specific MCP capability or utility your server supports, there is a |
| corresponding mixin that you can use (`ToolsSupport`, `ResourcesSupport`, etc). |
| |
| Each mixin has doc comments explaining how to use it - some may require you to |
| provide implementations of methods, while others may just expose new methods |
| that you can call. |
| |
| See the [server example](example/simple_server.dart) for some example code. |
| |
| ### Invoking Client Capabilities |
| |
| All client capabilities are exposed as methods on the `MCPServer` class. |
| |
| Before attempting to call these methods, you must first wait for the |
| `MCPServer.initialized` future and then check the capabilities of the |
| client by reading the `MCPServer.clientCapabilities`. |
| |
| Alternatively, if your server requires certain capabilities from the client for |
| all operations, you may override the `MCPServer.initialize` function and return |
| an error, which may result in a better UX for the users of the client. |
| |
| ## Implementing Clients |
| |
| To implement a client, import `package:dart_mcp/client.dart` and extend the |
| `MCPClient` class, or directly call its constructor with a |
| `Implementation` if you aren't implementing any "capabilities". |
| |
| For each specific MCP capability your client supports, there is a corresponding |
| mixin that you can use (`RootsSupport`, `SamplingSupport`, etc). Each mixin has |
| doc comments explaining how to use it - some may require you to provide |
| implementations of methods, while others may just expose new methods that you |
| can call. |
| |
| ### Connecting to Servers |
| |
| You can connect this client with STDIO servers using the |
| `MCPClient.connectStdioServer` method, or you can call `MCPClient.connectServer` |
| with any other communication channel. |
| |
| The returned `ServerConnection` should be used for all interactions with the |
| server, starting with a call to `ServerConnection.initialize`, followed up with |
| a call to `ServerConnection.notifyInitialized` (if initialization was |
| successful). If a version could not be negotiated or a server does not support |
| required features, the server connection should be closed (by calling |
| `ServerConnection.shutdown`). |
| |
| See [initialization lifecycle][initialization_lifecycle] for information about |
| the client/server initialization protocol. |
| |
| ### Invoking Server Capabilities and Utilities |
| |
| All server capabilities and utilities are exposed as methods or streams on the |
| `ServerConnection` class. |
| |
| Before attempting to call methods on the server however, you should first verify |
| the capabilities of the server by reading them from the `InitializeResult` returned |
| from `ServerConnection.initialize`. |
| |
| [initialization_lifecycle]: https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/lifecycle/#initialization |
| |
| ## Supported Protocol Versions |
| |
| [2024-11-05](https://spec.modelcontextprotocol.io/specification/2024-11-05/) |
| |
| If support for a given protocol version is dropped, that will be released as a |
| breaking change in this package. |
| |
| However, we will strive to maintain backwards compatibility where possible. |
| |
| ## Base Utilities |
| |
| This table describes the state of implementation for the base protocol |
| [utilities](https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/utilities). |
| |
| Both the `MCPServer` and `MCPClient` support these. |
| |
| | Utility | Support | Notes | |
| | --- | --- | --- | |
| | [Ping](https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/utilities/ping) | :heavy_check_mark: | | |
| | [Cancellation](https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/utilities/cancellation/) | :x: | https://github.com/dart-lang/ai/issues/37 | |
| | [Progress](https://spec.modelcontextprotocol.io/specification/2024-11-05/basic/utilities/progress/) | :heavy_check_mark: | | |
| |
| ## Transport Mechanisms |
| |
| This table describes the supported |
| [transport mechanisms](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports). |
| |
| At its core this package is just built on streams, so any transport mechanism |
| can be used, but some are directly supported out of the box. |
| |
| | Transport | Support | Notes | |
| | --- | --- | --- | |
| | [Stdio](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#stdio) | :heavy_check_mark: | | |
| | [Streamable HTTP](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#streamable-http) | :x: | Unsupported at this time, may come in the future. | |
| |
| ## Batching Requests |
| |
| Both the client and server support processing batch requests, but do not support |
| creating batch requests at this time. |
| |
| ## Authorization |
| |
| Authorization is not supported at this time. This package is primarily targeted |
| at local MCP server usage for now. |
| |
| ## Server Capabilities |
| |
| This table describes the state of implementation for the |
| [server capabilities](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/). |
| |
| **Note:** Servers can also invoke all [client capabilities](#client-capabilities), |
| see [Invoking Client Capabilities](#invoking-client-capabilities). |
| |
| | Capability | Support | Notes | |
| | --- | --- | --- | |
| | [Prompts](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/prompts/) | :heavy_check_mark: | | |
| | [Resources](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/resources/) | :heavy_check_mark: | | |
| | [Tools](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/tools/) | :heavy_check_mark: | | |
| |
| ## Server Utilities |
| |
| This table describes the state of implementation for the |
| [server utilities](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/utilities/). |
| |
| | Utility | Support | Notes | |
| | --- | --- | --- | |
| | [Completion](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/utilities/completion/) | :heavy_check_mark: | | |
| | [Logging](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/utilities/logging/) | :heavy_check_mark: | | |
| | [Pagination](https://spec.modelcontextprotocol.io/specification/2024-11-05/server/utilities/pagination/) | :construction: | https://github.com/dart-lang/ai/issues/28 | |
| |
| ## Client Capabilities |
| |
| This table describes the state of implementation for the client |
| [capabilities](https://spec.modelcontextprotocol.io/specification/2024-11-05/client/). |
| |
| **Note:** Clients can also invoke all [server capabilities](#server-capabilities) |
| and [server utilities](#server-utilities), |
| see [Invoking Server Capabilities and Utilities](#invoking-server-capabilities-and-utilities). |
| |
| | Capability | Support | Notes | |
| | --- | --- | --- | |
| | [Roots](https://spec.modelcontextprotocol.io/specification/2024-11-05/client/roots/)| :heavy_check_mark: | | |
| | [Sampling](https://spec.modelcontextprotocol.io/specification/2024-11-05/client/sampling/)| :heavy_check_mark: | | |
