mcpls MCP server

Commit Nov 15, 2026

bug-ops/mcpls · rust · Apache-2.0

Exposes language server intelligence like type information, references, and diagnostics as MCP tools for AI coding agents.

Also known as bug-ops/mcpls

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Stars: 83
Tools: —
Downloads, 30 days: —
Latest version: 0.10.0
Last commit: Nov 15, 2026
License: Apache-2.0

What is mcpls MCP?

mcpls exposes language server intelligence like type information, references, and diagnostics as MCP tools for AI coding agents.

Summary generated from the project's README

About mcpls MCP server

mcpls acts as a bridge between the Model Context Protocol and the Language Server Protocol to provide AI coding agents with deep technical insights. By running existing language servers like rust-analyzer, pyright, or gopls, it exposes 31 specific MCP tools that allow an AI client to access type information, references, diagnostics, and refactoring capabilities. This setup enables an AI to reason about a codebase with the same precision as a professional integrated development environment.

Developers can install the server via curl, PowerShell, or Cargo and connect it to clients such as Claude Code. While Rust projects work without extra setup, other languages may require configuration. The server supports multiple language servers running concurrently in a polyglot project and offers an untrusted-workspace mode for safer analysis. It uses stdio by default but also supports HTTP transport with allowlists for more complex environments.

What you can do with it

1Retrieve specific type informationAn AI agent can identify the exact return type of a function using hover tools.
2Locate code referencesA developer can ask the agent to find every instance where a specific error or symbol is handled.
3Perform codebase refactoringThe agent can use compiler-backed tools to execute renames and code-action edits.
4Search polyglot workspacesUsers can search for symbols across different programming languages within a single project.

Written from the project's README. Every use case is checked against a quote from it.

Automated checks

Ran Nov 12, 2026Full report →

92/100

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README

View on GitHub

mcpls

Give your AI coding agent a compiler's understanding of your code.

mcpls is a bridge between the Model Context Protocol (MCP) and the Language Server Protocol (LSP). It runs the language servers for your project (rust-analyzer, pyright, gopls, and others) and exposes their type information, references, diagnostics and refactoring as 31 MCP tools, so an AI client reasons about code the way an IDE does.

flowchart LR
    C["AI client"] <-->|MCP| M["mcpls"] <-->|LSP| S["rust-analyzer / pyright / gopls / ..."]

Documentation

The full documentation is the mcpls book: https://bug-ops.github.io/mcpls/

Topic	Chapter
Install and first run	Installation
Connect Claude Code or another client	Connect an AI Client
Configure language servers	Configuration
All 31 tools	Tools Overview
Something does not work	Troubleshooting
HTTP transport and allowlists	Transports
Security model and untrusted workspaces	Security and Trust
Every flag and config key	Reference

Installation

Linux and macOS:

curl -fsSL https://raw.githubusercontent.com/bug-ops/mcpls/main/scripts/install.sh | sh

Windows (PowerShell):

irm https://raw.githubusercontent.com/bug-ops/mcpls/main/scripts/install.ps1 | iex

Or with Cargo:

cargo install mcpls

Prebuilt archives for Linux, macOS and Windows (x86_64 and aarch64) with SHA256 checksums and build-provenance attestations are on GitHub Releases.

mcpls is also listed in the official MCP Registry as io.github.bug-ops/mcpls (cargo package, stdio transport), so registry-aware clients can discover it there. The listing installs the same crate as cargo install mcpls.

You also need at least one language server, for example rustup component add rust-analyzer. See Installation for other methods and servers.

Quick start

claude mcp add --scope user mcpls -- mcpls

Then ask about your code:

You:    What is the return type of process_request?
Claude: [get_hover] It returns Result<Response, ApiError>.

You:    Find everywhere ApiError::Timeout is handled.
Claude: [get_references] Found 4 matches: src/handlers/api.rs:89, ...

Rust projects need no configuration. Other languages and clients are covered in the book.

Features

Type information and documentation at any position
Cross-references, definitions, implementations across the whole workspace
Real diagnostics from the compiler, not guesses
Rename and code-action edits returned for the client to apply
Call and type hierarchies, formatting, inlay hints, selection and folding ranges
Workspace symbol search across every language server of a polyglot project, with each symbol tagged by its server
Address code by symbol name as well as by position, and restart language servers on demand
Several language servers at once, started concurrently and stopped with mcpls, with graceful degradation when one fails
stdio by default, optional HTTP transport with Host and Origin allowlists and resource subscriptions
Untrusted-workspace mode for analyzing code you do not trust
Single Rust binary, no runtime dependencies, no unsafe code; release archives carry build-provenance attestations

Security

Language servers run code that comes with the workspace, and mcpls does not sandbox them. Read SECURITY.md and the Security and Trust chapter before pointing mcpls at code you did not write.

Agent skill

skills/mcpls is a packaged Agent Skill that teaches an AI coding agent to install, configure and run mcpls.

Development

cargo build
cargo nextest run --workspace --all-features

Requires Rust 1.99 or later (edition 2024). The book lives in book/ and is built with mdBook. See CONTRIBUTING.md.

Community

Participation is governed by the Code of Conduct. Accessibility of the output and documentation is described in ACCESSIBILITY.md.

License

Dual-licensed under Apache 2.0 or MIT at your option.

Read full README

mcpls MCP questions

What does mcpls do?

It acts as a bridge between the Model Context Protocol and the Language Server Protocol, allowing AI clients to use language server features like type information and refactoring.

Is mcpls secure for untrusted code?

Language servers run code from the workspace and mcpls does not sandbox them, so you should read the security documentation before using it on untrusted code.

Does it support multiple languages?

Yes, it can run several language servers concurrently, such as rust-analyzer, pyright, and gopls.

Facts

Nov 15, 2026

Stars: 83
Downloads, 30 days: —
Latest version: 0.10.0
Last commit: Nov 15, 2026
License: Apache-2.0
Transport: stdio
Package: mcpls

bug-ops ↗

Community publisher

Published by an independent maintainer.

Alternatives

Works with

Claude Code Cursor VS Code Claude Desktop Codex Gemini CLI Windsurf Devin

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Before you install

Servers run with the permissions you give them. Use the narrowest token or database role that does the job.

About mcpls MCP server

What you can do with it

1Retrieve specific type informationAn AI agent can identify the exact return type of a function using hover tools.
2Locate code referencesA developer can ask the agent to find every instance where a specific error or symbol is handled.
3Perform codebase refactoringThe agent can use compiler-backed tools to execute renames and code-action edits.
4Search polyglot workspacesUsers can search for symbols across different programming languages within a single project.

Written from the project's README. Every use case is checked against a quote from it.

Topic

Chapter

Install and first run

Installation

Connect Claude Code or another client

Connect an AI Client

Configure language servers

Configuration

All 31 tools

Tools Overview

Something does not work

Troubleshooting

HTTP transport and allowlists

Transports

Security model and untrusted workspaces

Security and Trust

Every flag and config key

Reference

You: What is the return type of process_request? Claude: [get_hover] It returns Result<Response, ApiError>. You: Find everywhere ApiError::Timeout is handled. Claude: [get_references] Found 4 matches: src/handlers/api.rs:89, ...