MCP Models

Dart model classes for the Model Context Protocol (MCP) 2025-11-25.

Every type defined in the official MCP schema is available as a plain Dart class with toMap() serialisation and a named factory TypeName.toMCP(Map) for deserialisation — no code generation required.

Features

• Full coverage of the MCP 2025-11-25 schema: JSON-RPC messages, tools, resources, prompts, sampling, elicitation, tasks, notifications and more.
• Zero runtime dependencies — pure Dart.
• McpBuilder helper for declarative server capability registration.
• MapMC<K,V> and MapModel<K,V> base classes for types whose serialised form is the underlying map.

Installation

dependencies:
  mcp_models: ^1.0.0

Or with the CLI:

dart pub add mcp_models

Quick start

import 'package:mcp_models/mcp_models.dart';

// Build an initialize request.
final request = InitializeRequest(
  id: '1',
  params: InitializeRequestParams(
    protocolVersion: '2025-11-25',
    capabilities: ClientCapabilities({}),
    clientInfo: Implementation(name: 'my_client', version: '1.0.0'),
  ),
);

// Serialise to a Map (ready for JSON encoding).
final json = request.toMap();

// Deserialise back.
final restored = InitializeRequest.toMCP(json);

McpBuilder

McpBuilder lets you declare all server capabilities in one place and look up handlers by name/URI at runtime:

final builder = McpBuilder();

builder.tool(
  name: 'add',
  description: 'Adds two integers.',
  inputSchema: ToolSchema(
    properties: {
      'a': {'type': 'integer'},
      'b': {'type': 'integer'},
    },
    required: ['a', 'b'],
  ),
  handler: (req) async {
    final args = req.params.arguments ?? {};
    final sum = (args['a'] as int) + (args['b'] as int);
    return CallToolResult(
      content: [TextContent(text: '$sum', mimeType: 'text/plain')],
    );
  },
);

builder.resource(
  name: 'config',
  uri: 'file:///config.json',
  handler: (req) async => ReadResourceResult(contents: []),
);

builder.prompt(
  name: 'greet',
  handler: (req) async => GetPromptResult(messages: []),
);

// Serve a tools/list response.
final toolsResult = builder.buildToolsResult();

// Dispatch a tools/call request.
final handler = builder.toolHandler('add');
if (handler != null) {
  final result = await handler(callToolRequest);
}

Supported MCP types

| Category | Types | |---|---| | JSON-RPC core | JSONRPCRequest, JSONRPCNotification, JSONRPCResultResponse, JSONRPCErrorResponse | | Errors | Error, ParseError, InvalidRequestError, MethodNotFoundError, InvalidParamsError, InternalError | | Initialization | InitializeRequest, InitializeRequestParams, InitializeResult, Implementation, ClientCapabilities, ServerCapabilities | | Tools | Tool, ToolSchema, ToolAnnotations, ToolExecution, CallToolRequest, CallToolResult, ListToolsResult | | Resources | Resource, ResourceTemplate, TextResourceContents, BlobResourceContents, ReadResourceResult, ListResourcesResult | | Prompts | Prompt, PromptArgument, PromptMessage, GetPromptResult, ListPromptsResult | | Sampling | CreateMessageRequest, CreateMessageResult, SamplingMessage, ModelPreferences, ModelHint, ToolChoice | | Elicitation | ElicitRequest, ElicitResult, StringSchema, NumberSchema, BooleanSchema, UntitledSingleSelectEnumSchema, TitledSingleSelectEnumSchema | | Tasks | Task, TaskStatus, TaskMetadata, ListTasksResult | | Content blocks | TextContent, ImageContent, AudioContent, EmbeddedResource, ResourceLink | | Notifications | InitializedNotification, CancelledNotification, ProgressNotification, LoggingMessageNotificationParams, ToolListChangedNotification, ResourceListChangedNotification | | Misc | PingRequest, EmptyResult, Annotations, Role, LoggingLevel, MetaObject, Icon, Theme |

See the example for end-to-end usage.

MCP specification

This package targets the MCP 2025-11-25 schema: https://modelcontextprotocol.io/specification/2025-11-25/schema

Contributing

Contributions, bug reports, and feature requests are very welcome!

We especially encourage Dart developers to open GitHub Issues to help guide the development and keep this package up to date with the evolving MCP specification.

Ways to contribute:

• Found a bug or missing type? Open a bug report

• Want a new feature or schema update? Open a feature request

• Want to submit code? See CONTRIBUTING.md.

Every issue, no matter how small, helps keep this package accurate and useful for the entire Dart community. Thank you!

License

MIT — see LICENSE.