ts-lsp-mcp

MCP server exposing TypeScript LSP-like functionality to AI agents.

Gives AI agents the same "what's the type at this position?" powers that IDE users have.

Quick Start

Install into Claude Code

# Install to current project (recommended)
npx ts-lsp-mcp install cc

# Or install globally for all projects
npx ts-lsp-mcp install cc --global

That's it! The MCP server is now available to Claude Code.

Uninstall

npx ts-lsp-mcp uninstall cc

Manual Installation

Global npm install

npm install -g ts-lsp-mcp
ts-lsp-mcp install cc

Manual config

Add to your Claude Code MCP config (.mcp.json in project or ~/.claude/settings.json globally):

{
  "mcpServers": {
    "ts-lsp-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "ts-lsp-mcp", "serve", "--stdio"]
    }
  }
}

HTTP/SSE Mode

For remote clients or debugging:

ts-lsp-mcp --http --port 3000

Endpoints:

GET /sse - SSE connection
POST /message - Send messages
GET /health - Health check

Available Tools

Tool	Description
`getTypeAtPosition`	Get the TypeScript type at a specific file:line:col
`getDefinition`	Go to definition
`getReferences`	Find all references
`getHover`	Get hover documentation
`getCompletions`	Get autocomplete suggestions
`getDiagnostics`	Get type errors and warnings
`traceType`	Trace where a type comes from and how it's composed
`runTypeTests`	Run type assertions from `@ts-lsp-mcp` comments
`checkInlineCode`	Type-check inline TypeScript without creating files

Type Test Assertions

Add type assertions to your code:

// @ts-lsp-mcp expect-type: string
const name = user.name;

// @ts-lsp-mcp expect-type: User
const user = createUser({ name: 'Alice' });

// @ts-lsp-mcp expect-error: 2322
const bad: number = "oops";  // Should have error 2322

Run tests:

runTypeTests({ file: "src/types.ts" })
runTypeTests({ pattern: "**/*.type-test.ts" })

Example Usage

Get type at position

Supports unified file:line:col format:

{
  "tool": "getTypeAtPosition",
  "arguments": {
    "file": "src/user.ts:10:5"
  }
}

Or separate parameters:

{
  "tool": "getTypeAtPosition",
  "arguments": {
    "file": "src/user.ts",
    "line": 10,
    "col": 5
  }
}

Response:

{
  "type": "User",
  "expanded": "{ id: number; name: string; email: string }",
  "symbol": "user",
  "kind": "variable"
}

Check for type errors

{
  "tool": "getDiagnostics",
  "arguments": {
    "file": "src/user.ts"
  }
}

Type-check inline code

{
  "tool": "checkInlineCode",
  "arguments": {
    "code": "const x: number = 'bad';"
  }
}