LSP MCP

An Model Context Protocol (MCP) server that provides LLMs/AI Agents with the capabilities of a language server protocol (LSP) server. This gives the AI the ability to get language aware context from the codebase.

• LSP MCP
  • Example
  • Warning
  • Features
  • Quick Start
    • Claude Desktop
      • Using Docker (Recommended)
      • Using npx
    • Cursor
    • MCP CLI Client
  • The ABCs (Introduction)
    • What is an MCP?
    • What is an LSP?
  • Development
    • Dependencies
    • Decisions
    • Roadmap
  • References

Example

Input:

Use lsp to give me insights into the following typescript code:

let foo = "bar";
function x() {
  let foo = 123;
  console.log(foo);
}
x();
console.log(foo);

Output:

I'll use LSP (Language Server Protocol) to analyze your TypeScript code. Let me break down what's happening:
Here's what the code does and the insights from LSP analysis:

1. Variable Shadowing:

There are two variables named foo:

A global foo (string type) initialized with the value "bar"
A local foo (number type) inside the function x() initialized with the value 123

2. Execution Flow:

First, the global foo is declared and assigned the value "bar"
When function x() is called, the local foo variable is declared and assigned 123
The console.log(foo) inside the function outputs 123 (the local variable)
After the function finishes, console.log(foo) outputs "bar" (the global variable)

3. Scope Isolation:

The LSP confirms that TypeScript correctly identifies the different types:

The global foo is a string type
The local foo inside the function is a number type

Changes to the local foo don't affect the global foo

This is a classic example of variable shadowing in JavaScript/TypeScript, where a local variable with the same name as a global variable takes precedence within its scope.

Warning

This is in a POC state.

Features

• Multiple LSPs (Multiple programming language support) at the same time, see sample config
• Dynamically generates supported LSP method from LSP JSON Schema, see json schema

Quick Start

Claude Desktop

Using Docker (Recommended)

Modify claude_desktop_config.json (As described in the MCP Docs) with the following:

{
  "mcpServers": {
    "lsp": {
      "command": "docker",
      "args": ["run", "-i", "--rm", "docker.io/jonrad/lsp-mcp:0.3.1"]
    }
  }
}

You'll likely want to share some files with the container by passing docker -v /local_dir:/remote_dir. Then you can ask Claude about the files in /remote_dir/<filename>.

Using npx

Note: Claude Desktop is finicky with npx it seems. Sometimes it says the mcp fails but the tools still work. I'll look into this... later 😊

{
  "mcpServers": {
    "lsp": {
      "command": "npx",
      "args": ["-y", "--silent", "git+https://github.com/jonrad/lsp-mcp", "--lsp", "npx -y --silent -p 'typescript@5.7.3' -p 'typescript-language-server@4.3.3' typescript-language-server --stdio"]
    }
  }
}

This will provide Claude with the LSP capabilities of the typescript language server. You can modify the language server by switching the --lsp argument (and then restarting Claude).

Multiple LSPs at the same time is not yet supported.

Cursor

Follow the instructions provided by Cursor. For settings, choose Type = command and Command = docker run ... as mentioned above for claude (eg `docker run -i --rm -v <LOCAL_DIR>:<REMOTE_DIR> jonra

... View full README on GitHub