mcp-types — MCP protocol types for Haskell

Core type definitions and JSON-RPC protocol layer for the Model Context Protocol (MCP).

This package contains only the pure protocol types with minimal dependencies, Implements MCP protocol version 2025-06-18, making it suitable for building both clients and servers on any framework. For a ready-made Servant-based server, see the mcp package.

Modules

• MCP.Types — Core MCP data types: Content, Resource, Tool, Prompt, Capability, Implementation, and more.
• MCP.Protocol — JSON-RPC 2.0 message wrappers, all client/server request/response types, notification types, and protocol constants. Re-exports the jsonrpc transport types.
• MCP.Aeson — Custom Aeson parsing options used internally.

Install

build-depends:
    base
  , aeson
  , mcp-types

MCP Protocol Support

Operation	Description
initialize	Start session and negotiate capabilities
ping	Health check
resources/list	List available resources
resources/templates/list	List resource templates
resources/read	Read resource contents
resources/subscribe	Subscribe to resource updates
resources/unsubscribe	Unsubscribe from resource updates
prompts/list	List available prompts
prompts/get	Get prompt with arguments
tools/list	List available tools
tools/call	Execute a tool
completion/complete	Auto-completion with context
logging/setLevel	Set logging level
sampling/createMessage	Request LLM sampling
roots/list	List client root directories
elicitation/create	Request user input via forms

License

MPL-2.0