Content
# MCP(Model Context Protocol) for Dart
[](https://pub.dev/packages/mcp_dart)
[](https://pub.dev/packages/mcp_dart/score)
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.
## 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 2025-06-18](https://modelcontextprotocol.io/specification/2025-06-18) implementation
- ✅ **Multiple Transport Options** - Stdio, StreamableHTTP, Stream, or custom transports
- ✅ **All Capabilities** - Tools, Resources, Prompts, Sampling, Roots, Completions, Elicitation
- ✅ **OAuth2 Support** - Complete authentication with PKCE
- ✅ **Type-Safe** - Comprehensive type definitions with null safety
- ✅ **Cross-Platform** - Works on VM, 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 `2025-06-18`. 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 `2025-03-26`, `2024-11-05`, and `2024-10-07`.
**New in 2025-06-18**: Elicitation support for server-initiated user input collection.
## Documentation
### Getting Started
- 📖 **[Quick Start Guide](https://github.com/leehack/mcp_dart/blob/main/doc/getting-started.md)** - Get up and running in 5 minutes
- 🔧 **[Server Guide](https://github.com/leehack/mcp_dart/blob/main/doc/server-guide.md)** - Complete guide to building MCP servers
- 💻 **[Client Guide](https://github.com/leehack/mcp_dart/blob/main/doc/client-guide.md)** - Complete guide to building MCP clients
### Core Concepts
- 🛠️ **[Tools Documentation](https://github.com/leehack/mcp_dart/blob/main/doc/tools.md)** - Implementing executable tools
- 🔌 **[Transport Options](https://github.com/leehack/mcp_dart/blob/main/doc/transports.md)** - Built-in and custom transport implementations
- 📚 **[Examples](https://github.com/leehack/mcp_dart/blob/main/doc/examples.md)** - Real-world usage examples
- ⚡ **[Quick Reference](https://github.com/leehack/mcp_dart/blob/main/doc/quick-reference.md)** - Fast lookup guide
### Advanced Features
- 🔐 **[OAuth Authentication](https://github.com/leehack/mcp_dart/blob/main/example/authentication/)** - OAuth2 guides and examples
- 📝 For resources, prompts, and other features, see the Server and Client guides
## Quick Start Example
Below is the simplest way to create an MCP server:
```dart
import 'package:mcp_dart/mcp_dart.dart';
void main() async {
McpServer server = McpServer(
Implementation(name: "mcp-example-server", version: "1.0.0"),
options: ServerOptions(
capabilities: ServerCapabilities(
resources: ServerCapabilitiesResources(),
tools: ServerCapabilitiesTools(),
),
),
);
server.tool(
"calculate",
description: 'Perform basic arithmetic operations',
toolInputSchema: ToolInputSchema(
properties: {
'operation': {
'type': 'string',
'enum': ['add', 'subtract', 'multiply', 'divide'],
},
'a': {'type': 'number'},
'b': {'type': 'number'},
},
required: ['operation', 'a', 'b'],
),
callback: ({args, extra}) async {
final operation = args!['operation'];
final a = args['a'];
final b = args['b'];
return CallToolResult.fromContent(
content: [
TextContent(
text: switch (operation) {
'add' => 'Result: ${a + b}',
'subtract' => 'Result: ${a - b}',
'multiply' => 'Result: ${a * b}',
'divide' => 'Result: ${a / b}',
_ => throw Exception('Invalid operation'),
},
),
],
);
},
);
server.connect(StdioServerTransport());
}
```
### Running Your Server
Compile your MCP server to an executable:
```bash
dart compile exe example/server_stdio.dart -o ./server_stdio
```
Or run it directly with JIT:
```bash
dart run example/server_stdio.dart
```
### Connecting to AI Hosts
To configure your server with AI hosts like Claude Desktop:
```json
{
"mcpServers": {
"calculator_jit": {
"command": "path/to/dart",
"args": [
"/path/to/server_stdio.dart"
]
},
"calculator_aot": {
"command": "path/to/compiled/server_stdio",
},
}
}
```
## Authentication
This library supports OAuth2 authentication with PKCE for both clients and servers. For complete authentication guides and examples, see the [OAuth Authentication documentation](https://github.com/leehack/mcp_dart/blob/main/example/authentication/).
## Platform Support
| Platform | Stdio | StreamableHTTP | Stream | Custom |
|----------|-------|----------------|--------|--------|
| **Dart VM** (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](https://github.com/leehack/mcp_dart/tree/main/example)
- [Authentication Examples](https://github.com/leehack/mcp_dart/tree/main/example/authentication)
## Community & Support
- **Issues & Bug Reports**: [GitHub Issues](https://github.com/leehack/mcp_dart/issues)
- **Package**: [pub.dev/packages/mcp_dart](https://pub.dev/packages/mcp_dart)
- **Protocol Spec**: [MCP Specification](https://modelcontextprotocol.io/specification/2025-06-18)
## Credits
This library is inspired by the following projects:
- <https://github.com/crbrotea/dart_mcp>
- <https://github.com/nmfisher/simple_dart_mcp_server>
