MCP (Model Context Protocol) for Dart

The Model Context Protocol (MCP) is a standardized protocol for communication between AI applications and external services. It enables:

• Tools: Allow AI to execute actions (API calls, computations, etc.)
• Resources: Provide context and data to AI (files, databases, APIs)
• Prompts: Pre-built prompt templates with arguments

Understanding MCP: Client, Server, and Host

MCP follows a client-server architecture with three key components:

• MCP Host: The AI application that provides the user interface and manages connections to multiple MCP servers.

  • Example: Claude Desktop, IDEs like VS Code, custom AI applications
  • Manages server lifecycle, discovers capabilities, and orchestrates interactions

• MCP Client: The protocol implementation within the host that communicates with servers.

  • Handles protocol negotiation, capability discovery, and request/response flow
  • Typically built into or used by the MCP host

• MCP Server: Provides capabilities (tools, resources, prompts) that AI can use through the host.

  • Example: Servers for file system access, database queries, or API integrations
  • Runs as a separate process and communicates via standardized transports (stdio, StreamableHTTP)

Typical Flow: User ↔ MCP Host (with Client) ↔ MCP Protocol ↔ Your Server ↔ External Services/Data

Requirements

• Dart SDK version ^3.0.0 or higher

Ensure you have the correct Dart SDK version installed. See https://dart.dev/get-dart for installation instructions.

Installation

Add to your pubspec.yaml:

dependencies:
  mcp_dart: ^2.1.1

Then install dependencies:

dart pub get

What This SDK Provides

This SDK lets you build both MCP servers and clients in Dart/Flutter.

• ✅ Build MCP Servers - Create servers that expose tools, resources, and prompts to AI hosts
• ✅ Build MCP Clients - Create AI applications that can connect to and use MCP servers
• ✅ Full MCP Protocol Support - Complete MCP specification 2025-11-25 implementation
• ✅ Multiple Transport Options - Stdio, StreamableHTTP, IOStream, or custom transports
• ✅ All Capabilities - Tools, Resources, Prompts, Sampling, Roots, Completions, Elicitation, Tasks
• ✅ Extension Support - Generic extensions negotiation with typed MCP Apps helpers and TypeScript-style registerAppTool / registerAppResource
• ✅ Latest Content/Metadata Types - resource_link, themed icons, and annotations.lastModified
• ✅ OAuth2 Support - Complete authentication with PKCE
• ✅ Transport Security Controls - DNS rebinding protection and strict Streamable HTTP validation with compatibility toggles
• ✅ Type-Safe - Comprehensive type definitions with null safety
• ✅ Cross-Platform - Works on Linux, Windows, macOS, Web, and Flutter

The goal is to make this SDK as similar as possible to the official SDKs available in other languages, ensuring a consistent developer experience across platforms.

Model Context Protocol Version

The current version of the protocol is 2025-11-25. This library is designed to be compatible with this version, and any future updates will be made to ensure continued compatibility.

It's also backward compatible with previous versions including 2025-06-18, 2025-03-26, 2024-11-05, and 2024-10-07.

Documentation

Getting Started

• 📖 Quick Start Guide - Get up and running in 5 minutes
• 🔧 Server Guide - Complete guide to building MCP servers
• 💻 Client Guide - Complete guide to building MCP clients

Core Concepts

• 🛠️ Tools Documentation - Implementing executable tools
• 🔌 Transport Options - Built-in and custom transport implementations
• 📚 Examples - Real-world usage examples
• ⚡ Quick Reference - Fast lookup guide
• 🪵 Runtime Logging - Configure and route internal SDK logs
• 🧩 MCP Apps Guide - Using io.modelcontextprotocol/ui metadata

Advanced Features

• 🔐 OAuth Authentication - OAuth2 guides and examples
• 🔁 2025-11-25 Compatibility Migration - Backward-compatible API/runtime migration notes
• 📝 For resources, prompts, and other features, see the Server and Client guides

Quick Start with CLI

The fastest way to create an MCP server is using the mcp_dart_cli:

# Install the CLI
dart pub global activate mcp_dart_cli

# Create a new project
mcp_dart create my_server

# Navigate and run
cd my_server
mcp_dart serve

Your server is now running! Use mcp_dart inspect to test it:

mcp_dart inspect              # List all capabilities
mcp_dart inspect --tool add --json-args '{"a": 1, "b": 2}'   # Call a tool

CLI Commands

Command	Description
create	Scaffold a new MCP server project
serve	Run your server (stdio or HTTP)
doctor	Check project health and connectivity
inspect	Test and debug server capabilities

📖 Full CLI Documentation

Connecting to AI Hosts

Configure your server with AI hosts like Claude Desktop:

{
  "mcpServers": {
    "my_server": {
      "command": "mcp_dart",
      "args": ["serve"],
      "cwd": "/path/to/my_server"
    }
  }
}

[!TIP] For manual server implementation or advanced use cases, see the Server Guide.

Authentication

This library supports OAuth2 authentication with PKCE for both clients and servers. For complete authentication guides and examples, see the OAuth Authentication documentation.

Platform Support

Platform	Stdio	StreamableHTTP	IOStream	Custom
Desktop (CLI/Server)	✅	✅	✅	✅
Web (Browser)	❌	✅	✅	✅
Flutter (Mobile/Desktop)	✅	✅	✅	✅

Custom Transports: You can implement your own transport layer by extending the transport interfaces if you need specific communication patterns not covered by the built-in options.

More Examples

For additional examples including authentication, HTTP clients, and advanced features:

• All Examples
• Authentication Examples

Community & Support

• Issues & Bug Reports: GitHub Issues
• Package: pub.dev/packages/mcp_dart
• API Docs: pub.dev documentation
• Changelog: CHANGELOG.md
• Protocol Spec: MCP Specification

Credits

This library is inspired by the following projects:

• https://github.com/crbrotea/dart_mcp
• https://github.com/nmfisher/simple_dart_mcp_server