mcpls

Overview

mcpls is a universal bridge between AI coding assistants and language servers. It exposes the full power of LSP — type inference, cross-reference analysis, semantic navigation — through the Model Context Protocol, enabling AI agents to reason about code the way IDEs do. This tool provides AI agents with type information, cross-references, semantic navigation, real diagnostics, and safe refactoring capabilities.

Try asking AI

After installing, here are 5 things you can ask your AI assistant:

• get_hover

  Type signatures, documentation, inferred types at any position

  Try:What's the return type of process_request on line 47?Try:Show me the documentation for this function
• get_definition

  Jump to where a symbol is defined — across files, across crates

  Try:Take me to the definition of this functionTry:Where is this struct defined?
• get_references

  Every usage of a symbol in your workspace

  Try:Find everywhere ApiError::Timeout is handledTry:Show all references to this variable
• get_completions

  Context-aware suggestions that respect types and scope

  Try:What methods are available on this object?Try:Complete this function call
• get_document_symbols

  Structured outline — functions, types, constants, imports

  Try:Show me an outline of this fileTry:What functions are in this module?
• workspace_symbol_search

  Find symbols by name across the entire workspace

  Try:Find all functions named 'process'Try:Search for 'Config' in the entire codebase
• get_diagnostics

  Real compiler errors and warnings, not guesses

  Try:Show me all errors in this fileTry:What diagnostics are present in the project?
• get_code_actions

  Quick fixes, refactorings, and source actions at a position

  Try:What fixes are available for this error?Try:Show me refactorings for this function
• rename_symbol

  Workspace-wide rename with full reference tracking

  Try:Rename this function to 'process_data'Try:Change this variable name throughout the project
• format_document

  Apply language-specific formatting rules

  Try:Format this documentTry:Clean up the formatting in this file
• get_incoming_calls

  Find all callers of a function (who calls this?)

  Try:Who calls this function?Try:Find all places that use this method
• get_outgoing_calls

  Find all callees of a function (what does this call?)

  Try:What does this function call?Try:Show all function calls inside this method

Comparable tools

Installation

cargo install mcpls

{
  "mcpServers": {
    "mcpls": {
      "command": "mcpls",
      "args": []
    }
  }
}

FAQ

Which language servers are supported?

mcpls works with any LSP 3.17 compliant server including rust-analyzer, pyright, typescript-language-server, gopls, clangd, jdtls, zls, and 24+ others.

Does mcpls require configuration?

No configuration needed for Rust projects with rust-analyzer. For other languages, mcpls uses smart heuristics to spawn only relevant language servers based on project markers.

On Hacker News

Recent discussion from the developer community.

• Language Server Protocol (LSP) for AI Coding Agents▲ 2💬 1
  Story by bug-ops · 2026-01-04

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