hs-mcp
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MCP-Haskell (hs-mcp) provides a Haskell implementation of the Model Context Protocol, allowing Haskell applications to expose tools, resources, and prompts to MCP-compatible clients like Claude.
MCP-Haskell (hs-mcp)
A Haskell implementation of the Model Context Protocol (MCP).
Overview
MCP-Haskell (hs-mcp) provides a Haskell implementation of the Model Context Protocol, allowing Haskell applications to expose tools, resources, and prompts to MCP-compatible clients like Claude.
Key features:
- Full implementation of MCP protocol
- StdIO transport for local process communication
- JSON-RPC messaging
- Support for resources, tools, and prompts
- Comprehensive test suite
Installation
# Clone the repository
git clone github.com:buecking/hs-mcp.git
cd hs-mcp
# direnv
# echo 'use flake' > .envrc
direnv allow
# nix
nix develop
# Build the project
cabal build
Usage
Creating a simple server
import Network.MCP.Server
import Network.MCP.Types
import Network.MCP.Server.StdIO
main :: IO ()
main = do
-- Create server
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 reading 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 with StdIO transport
runServerWithSTDIO server
Example Server
The project includes an example echo server that demonstrates the MCP functionality:
# Build and run the example server
cabal run mcp-echo-server
You can test it with the MCP Inspector or Claude Desktop.
Testing
Run the test suite:
cabal test
Protocol Compatibility
This implementation follows the Model Context Protocol specification and is compatible with:
- Claude Desktop
- MCP Inspector
- Other MCP clients following the specification
Project Structure
src/Network/MCP/Types.hs- Core MCP typessrc/Network/MCP/Transport/- Transport implementationssrc/Network/MCP/Server/- Server implementationExamples/- Example implementationsTest/- Test suite
Contributing
Contributions are welcome! Please feel free to submit a Pull Request.
License
This project is licensed under the BSD-3-Clause License - see the LICENSE file for details.
