TypeScript Definition Finder MCP Server

A Model Context Protocol (MCP) server that helps AI code editors find TypeScript symbol definitions in your codebase. This tool is particularly useful when you need to locate the original definition of imported symbols, classes, interfaces, or functions in a TypeScript project.

Features

• Finds original definitions of TypeScript symbols
• Works with imported symbols from external packages
• Returns both the definition location and code snippet
• Supports stdio interface for seamless integration with AI code editors

Prerequisites

• Bun v1.2.2 or later
• Node.js for running the compiled server

Installation

Installing via Smithery

To install TypeScript Definition Finder for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install @runninghare/ts-def-mcp --client claude

Manual Installation

1. Install dependencies:

bun install

2. Build the project:

bun run build

Usage

Start the stdio server:

node dist/run.js

Tool Description

The server provides a find_typescript_definition tool with the following capabilities:

• Tool Name: find_typescript_definition
• Trigger Command: /ts-def (Useful in Cursor if you want to force AI editor to find the referenced symbol definition)
• Purpose: Locates the original definition of TypeScript symbols in your codebase

Input Parameters

The tool requires three parameters:

1. file_path (string):

   • The absolute path to the current TypeScript file
   • Example: /path/to/your/project/src/index.ts

2. line_content (string):

   • The entire line containing the symbol you want to find the definition of
   • Used to locate the correct line in the file
   • Must match the line exactly as it appears in the file

3. column_number (number):

   • The 1-based column number where the symbol starts
   • Must be the exact column position of the symbol's first character

Examples

1. Finding an Imported Symbol Definition

Given this import statement:

import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";

To find the definition of StdioServerTransport, which starts at column 10, you would use:

{
  "file_path": "~/my-mcp-project/src/index.ts",
  "line_content": "import { StdioServerTransport } from \"@modelcontextprotocol/sdk/server/stdio.js\";",
  "column_number": 10
}

The output of this tool will be:

[
  {
    "file": "~/my-mcp-project/node_modules/@modelcontextprotocol/sdk/dist/esm/server/stdio.d.ts",
    "type": "Definition",
    "location": "Line 9, Column 22",
    "codeSnippet": "   8    */\n   9 > export declare class StdioServerTransport implements Transport {\n  10 +     private _stdin;\n  11 +     private _stdout;\n  12 +     private _readBuffer;\n  13 +     private _started;\n  14 +     constructor(_stdin?: Readable, _stdout?: Writable);\n  15 +     onclose?: () => void;\n  16 +     onerror?: (error: Error) => void;\n  17 +     onmessage?: (message: JSONRPCMessage) => void;\n  18 +     _ondata: (chunk: Buffer) => void;\n  19 +     _onerror: (error: Error) => void;\n  20 +     /**\n  21 +      * Starts listening for messages on stdin.\n  22 +      */\n  23 +     start(): Promise<void>;\n  24 +     private processReadBuffer;\n  25 +     close(): Promise<void>;\n  26 +     send(message: JSONRPCMessage): Promise<void>;\n  27   }\n"
  }
]

2. Finding a Local Symbol Definition

For a local class usage:

class MyService {
  private transport: StdioServerTransport;
}

To find the definition of StdioServerTransport, which starts at column 20, use:

{
  "file_path": "/path/to/project/src/service.ts",
  "line_content": "  private transport: StdioServerTransport;",
  "column_number": 20
}

Response Format

The tool returns a JSON response containing:

• The file path where the definition was found
• The line number of the definition
• The actual code snippet of the definition

Claude Desktop Example

<img width="766" alt="2025-03-16_19-15-46" src="https://github.com/user-attachments/assets/cbb7cd44-cf3c-430f-a281-0b6187ab3235" />

Development

This project was created using bun init in bun v1.2.2. Bun is a fast all-in-one JavaScript runtime.

Running in Development Mode

For development, you can run the server directly using Bun:

bun run index.ts

License

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Contributing

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