Copyright	(C) 2025 Matthias Pall Gissurarson
License	MIT
Maintainer	mpg@mpg.is
Stability	experimental
Portability	GHC
Safe Haskell	Safe-Inferred
Language	GHC2021

MCP.Server

Contents

Server Interface
Message Handling
Server Runner
Utilities

Description

This module provides a complete MCP server implementation, including message handling, state management, and JSON-RPC communication over standard input/output streams.

Synopsis

class Monad m => MCPServer m where
- handleListResources :: ListResourcesParams -> m ListResourcesResult
- handleReadResource :: ReadResourceParams -> m ReadResourceResult
- handleListResourceTemplates :: ListResourceTemplatesParams -> m ListResourceTemplatesResult
- handleListPrompts :: ListPromptsParams -> m ListPromptsResult
- handleGetPrompt :: GetPromptParams -> m GetPromptResult
- handleListTools :: ListToolsParams -> m ListToolsResult
- handleCallTool :: CallToolParams -> m CallToolResult
- handleComplete :: CompleteParams -> m CompleteResult
- handleSetLevel :: SetLevelParams -> m ()
data ServerState = ServerState {
- serverInitialized :: Bool
- serverCapabilities :: ServerCapabilities
- clientCapabilities :: Maybe ClientCapabilities
- serverInfo :: Maybe Implementation
- subscriptions :: Map Text ()
}
type MCPServerM = ReaderT ServerConfig (StateT ServerState (ExceptT Text IO))
runMCPServer :: ServerConfig -> ServerState -> MCPServerM a -> IO (Either Text (a, ServerState))
handleMessage :: MCPServer MCPServerM => ByteString -> MCPServerM (Maybe ())
handleRequest :: MCPServer MCPServerM => JSONRPCRequest -> MCPServerM ()
handleNotification :: JSONRPCNotification -> MCPServerM ()
runServer :: MCPServer MCPServerM => ServerConfig -> IO ()
data ServerConfig = ServerConfig {
- configInput :: Handle
- configOutput :: Handle
- configServerInfo :: Implementation
- configCapabilities :: ServerCapabilities
}
sendResponse :: (MonadIO m, ToJSON a) => Handle -> RequestId -> a -> m ()
sendNotification :: (MonadIO m, ToJSON a) => Handle -> Text -> a -> m ()
sendError :: MonadIO m => Handle -> RequestId -> JSONRPCErrorInfo -> m ()

Server Interface

class Monad m => MCPServer m where Source #

Type class for implementing MCP server handlers

data ServerState Source #

Server state tracking initialization, capabilities, and subscriptions

Constructors

ServerState
Fields serverInitialized :: Bool serverCapabilities :: ServerCapabilities clientCapabilities :: Maybe ClientCapabilities serverInfo :: Maybe Implementation subscriptions :: Map Text ()

Instances

Instances details

Show ServerState Source #
Instance details Defined in MCP.Server Methods showsPrec :: Int -> ServerState -> ShowS # show :: ServerState -> String # showList :: [ServerState] -> ShowS #

type MCPServerM = ReaderT ServerConfig (StateT ServerState (ExceptT Text IO)) Source #

The monad stack for MCP server operations

runMCPServer :: ServerConfig -> ServerState -> MCPServerM a -> IO (Either Text (a, ServerState)) Source #

Run an MCPServerM computation with the given config and initial state

Message Handling

handleMessage :: MCPServer MCPServerM => ByteString -> MCPServerM (Maybe ()) Source #

Handle an incoming JSON-RPC message

handleRequest :: MCPServer MCPServerM => JSONRPCRequest -> MCPServerM () Source #

Handle a JSON-RPC request

handleNotification :: JSONRPCNotification -> MCPServerM () Source #

Handle a JSON-RPC notification

Server Runner

runServer :: MCPServer MCPServerM => ServerConfig -> IO () Source #

Run the MCP server with the given configuration

data ServerConfig Source #

Configuration for running an MCP server

Constructors

ServerConfig
Fields configInput :: Handle configOutput :: Handle configServerInfo :: Implementation configCapabilities :: ServerCapabilities

Instances

Instances details

Show ServerConfig Source #
Instance details Defined in MCP.Server Methods showsPrec :: Int -> ServerConfig -> ShowS # show :: ServerConfig -> String # showList :: [ServerConfig] -> ShowS #

Utilities

sendResponse :: (MonadIO m, ToJSON a) => Handle -> RequestId -> a -> m () Source #

Send a JSON-RPC response

sendNotification :: (MonadIO m, ToJSON a) => Handle -> Text -> a -> m () Source #

Send a JSON-RPC notification

sendError :: MonadIO m => Handle -> RequestId -> JSONRPCErrorInfo -> m () Source #

Send a JSON-RPC error response