使用说明
Clojure MCP SDK
A composable Clojure SDK for building Model Context Protocol (MCP) servers, built on parts.ring.
Tools, prompts, and resources are defined as plain data maps. The SDK provides Ring handlers that plug into any parts.ring system. You bring your own HTTP server and own the session state.
Features
- MCP Protocol: Implements the MCP specification (protocol version 2025-06-18)
- Streamable HTTP Transport: HTTP/SSE via parts.ring + httpkit
- Data-driven: Tools, prompts, resources are registration entries (plain maps)
- Composable: Handlers integrate into any parts.ring system
- Bring your own server: httpkit included, but core handlers are server-agnostic
Quick Start
Add to your deps.edn:
{:deps {simplemono/mcp {:git/url "https://github.com/simplemono/mcp"
:git/sha "..."}}}
Create an MCP server:
(ns my-mcp-server
(:require [parts.mcp :as mcp]
[parts.ring.route]
[parts.httpkit.server :as server]))
;; Define tools as data
(def tools
[(mcp/tool {:name "greet"
:description "Sends a personalized greeting"
:malli [:map [:name string?]]
:handler (fn [_w {:keys [name]}]
{:content [{:type "text" :text (str "Hello, " name "!")}]
:isError false})})])
;; Define prompts as data
(def prompts
[(mcp/prompt {:name "joke-rating"
:description "Rate how funny a joke is"
:arguments [{:name "joke" :description "The joke to rate" :required true}]
:handler (fn [_w {:keys [joke]}]
[{:role "user"
:content {:type "text"
:text (str "Rate this joke from 1-5:\n\n" joke)}}])})])
;; Session state (user-provided atom)
(def sessions (atom {}))
;; Registration function - concatenates all entries
(defn get-register []
(concat tools
prompts
(mcp/routes)
parts.ring.route/register))
;; System / world map
(def system
(atom {:system/get-register #'get-register
:mcp/sessions sessions
:mcp/server-info {:name "My MCP Server" :version "1.0.0"}
:mcp/capabilities mcp/default-capabilities
:mcp/protocol-version mcp/protocol-version}))
;; Start
(server/start! system {:port 3999})
Registration Entries
Each helper returns a plain map that goes into the parts.ring register:
mcp/tool
(mcp/tool {:name "add"
:description "Adds two numbers"
:malli [:map [:a number?] [:b number?]] ;; or :schema for raw JSON Schema
:handler (fn [w args] {:content [{:type "text" :text (str (+ (:a args) (:b args)))}]})})
mcp/prompt
(mcp/prompt {:name "summarize"
:description "Summarize text"
:arguments [{:name "text" :description "Text to summarize" :required true}]
:handler (fn [w args] [{:role "user" :content {:type "text" :text (:text args)}}])})
mcp/resource
(mcp/resource {:uri "info://readme"
:name "README"
:description "Project readme"
:mimeType "text/plain"
:handler (fn [w] {:contents [{:uri "info://readme" :text (slurp "README.md")}]})})
mcp/resource-template
(mcp/resource-template {:uriTemplate "file:///{path}"
:name "File"
:description "Read a file"
:handler (fn [w uri] {:contents [{:uri uri :text (slurp uri)}]})})
Endpoints
(mcp/routes) returns three route entries:
| Method | Path | Description |
|---|---|---|
| POST | /mcp |
JSON-RPC requests, notifications, responses |
| GET | /mcp |
SSE notification stream |
| DELETE | /mcp |
Session termination |
Customize the path with (mcp/routes {:path "/my-mcp"}).
Dynamic Notifications
When tools/prompts/resources change at runtime, notify connected clients:
(mcp/notify-tools-changed! sessions)
(mcp/notify-prompts-changed! sessions)
(mcp/notify-resources-changed! sessions)
Examples
See the examples/ directory:
httpkit_server.clj- Full example with tools, prompts, and resourcessimple_mcp_server.clj- Minimal serverweather_server.clj- Weather tools using the NWS API
Run an example:
clj -M:example -m httpkit-server
Acknowledgements
Based on the Gaiwan MCP SDK.
License
Apache License, Version 2.0.
