MCP Codegen

Dart Build Status

A build_runner generator that turns mcp_annotations into concrete Model Context Protocol implementations.

Given a Dart package that uses @MCPTool or @MCPServerApp from mcp_annotations, this builder produces:

  • JSON tool descriptors that can be read by any MCP-compatible client.
  • Handler stubs that route an MCP invocation to your annotated Dart function.
  • Boot-strapped MCPServer subclasses that wire everything together.

Installing

Add the generator and its companion annotations package to your project:

# pubspec.yaml
name: my_app
# ...
dependencies:
  mcp_annotations: ^0.1.0

dev_dependencies:
  build_runner: ^2.4.0
  mcp_codegen: ^0.1.0

Note – mcp_codegen should only appear under dev_dependencies as it is never used at runtime.

Running the generator

# One-off build
$ dart run build_runner build

# Continuous build
$ dart run build_runner watch

Configuration

The generator exposes a single option, output_extensions, allowing you to change the suffix for generated files. The default is .mcp.g.dart.

# build.yaml
builders:
  mcp_codegen|mcpBuilder:
    options:
      output_extensions: '.my_mcp.g.dart'

Contributing

Please see the top-level CONTRIBUTING.md file for guidance on how to file bugs and submit pull-requests.

Libraries

mcp_codegen