nREPL MCP Server

MCPOpen Source46.3

by JohanCodinha • Tools & CLI

An MCP server that connects MCP clients to a running Clojure nREPL, enabling code evaluation, namespace inspection, and REPL-driven tooling for LLM-based clients.

Example Use Cases

1
Evaluate arbitrary Clojure expressions in a live REPL session to run tests, experiment with code, or compute results during a workflow.
2
Inspect project namespaces and public vars (including docstrings and values) to provide code-aware assistance, documentation, or refactoring suggestions.
3
Monitor and report nREPL connection status (host, port, session ID, and errors) to manage remote REPL sessions and debugging workflows.

Description

This MCP server bridges MCP clients (like Claude Desktop or CLine) with a running Clojure nREPL instance, allowing evaluation of Clojure code, inspection of namespaces, and retrieval of var metadata and connection status. It can be run via npx for quick usage or installed and built from source for development. The server communicates over STDIO and is designed to let language-model-driven tools interact with a live REPL for debugging, exploration, and automation. It supports listing project namespaces (via tools.namespace), inspecting public vars, and reporting nREPL connection details.

Capabilities(5 total)

Tools (3)

connect

Connect to an nREPL server. Example: (connect {:host "localhost" :port 1234})

host:string*port:number*

eval_form

Evaluate Clojure code in a specific namespace or the current one. Examples: - Define and call a function: {"code": "(defn greet [name] (str \"Hello, \" name \"!\"))(greet \"World\"))"} - Reload code: {"code": "(clj-reload.core/reload)"} - Evaluate in a specific namespace: {"code": "(clojure.repl.deps/sync-deps)", "ns": "user"}

code:string*ns:string

get_ns_vars

Get all public vars (functions, values) in a namespace with their metadata and current values. Example: - List main namespace vars: (get_ns_vars {:ns "main"}) Returns a map where keys are var names and values contain: - :meta - Metadata including :doc string, :line number, :file path - :value - Current value of the var

ns:string*

Resources (2)

nREPL Connection Status

Returns the current nREPL connection status including port and session information

URI: nrepl://statusMIME: application/json

Project Namespaces

Returns a list of all namespaces in the current project

URI: nrepl://namespacesMIME: application/json

Quick Actions

View on GitHub

Security

Scanned 3 month(s) ago

Risk Level

MINIMAL

Read-only data retrieval, no side effects

Trust Score

D43/100

4/17 checks passed

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Quick Stats

Service TypeMCP

Pricing ModelFree

Capabilities3 Tools / 0 Prompts / 2 Resources

OwnerJohanCodinha

CategoryTools & CLI

DependenciesStandalone

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