Hs MCP

🚀 MCP-Haskell (hs-mcp)

An implementation of the Model Context Protocol (MCP) in Haskell, allowing Haskell applications to expose tools, resources, and prompts to MCP-compatible clients such as Claude.

🚀 Quick Start

MCP-Haskell (hs-mcp) offers a complete implementation of the MCP protocol. It supports StdIO transmission for local inter-process communication, JSON-RPC message passing, and provides support for resources, tools, and prompts. Additionally, it comes with a comprehensive test suite.

📦 Installation

# Clone the repository
git clone github.com:buecking/hs-mcp.git
cd hs-mcp

# direnv configuration
# echo 'use flake' > .envrc
direnv allow

# Nix environment setup
nix develop

# Compile the project
cabal build

💻 Usage Examples

Basic Usage

import Network.MCP.Server
import Network.MCP.Types
import Network.MCP.Server.StdIO

main :: IO ()
main = do
  -- Create a server instance
  let serverInfo = Implementation "my-server" "1.0.0"
      serverCapabilities = ServerCapabilities
        { resourcesCapability = Just $ ResourcesCapability True
        , toolsCapability = Just $ ToolsCapability True
        , promptsCapability = Nothing
        }
  
  server <- createServer serverInfo serverCapabilities
  
  -- Register resources (optional)
  let resource = Resource 
        { resourceUri = "my://resource"
        , resourceName = "My Resource"
        , resourceDescription = Just "Description"
        , resourceMimeType = Just "text/plain"
        , resourceTemplate = Nothing
        }
  
  registerResources server [resource]
  
  -- Register resource read handler
  registerResourceReadHandler server $ \request -> do
    -- Implement resource read logic
    ...

  -- Register tools (optional)
  let tool = Tool 
        { toolName = "my-tool"
        , toolDescription = Just "My tool"
        , toolInputSchema = "{...}" -- JSON schema
        }
  
  registerTools server [tool]
  
  -- Register tool call handler
  registerToolCallHandler server $ \request -> do
    -- Implement tool execution logic
    ...
  
  -- Start the server using StdIO transmission
  runServerWithSTDIO server

Advanced Usage

The project includes an example echo server that demonstrates MCP functionality:

# Build and run the example server
cabal run mcp-echo-server

You can test it using the MCP Inspector or Claude Desktop.

📚 Documentation

Testing

Run the test suite:

cabal test

Protocol Compatibility

This implementation adheres to the Model Context Protocol Specification and is compatible with the following clients:

• Claude Desktop
• MCP Inspector
• Other MCP clients that follow the specification

Project Structure

• src/Network/MCP/Types.hs - Core MCP types
• src/Network/MCP/Transport/ - Transport implementations
• src/Network/MCP/Server/ - Server implementations
• Examples/ - Example implementations
• Test/ - Test suite

Contribution

Contributions are welcome! Feel free to submit a Pull Request.

📄 License

This project is licensed under the BSD-3-Clause License. See the LICENSE file for details.