🔌 grammar-coach — an MCP Server

A Model Context Protocol (MCP) server, built from scratch with the official Python SDK, that exposes grammar and readability analysis as callable tools to any MCP host (Claude Desktop, Cursor, etc.).

Built by: Mohammed Abdul Najeeb

💡 This is a hand-built MCP server demonstrating correct tool design — the core of the Model Context Protocol. It pairs with my VoiceCoach Lite app, which uses the same analysis engine in a web UI.

What is MCP (in one line)?

MCP is a standard protocol — "USB-C for AI" — that lets any AI host call tools and read data from any server. This repo is the server side: it publishes tools, and the AI host decides when to call them. The host decides; the server runs the code.

Related MCP server: content-qa-mcp

The tools this server exposes

Each tool follows deliberate design rules (see below).

Tool-design principles applied

This server is a worked example of good MCP tool design:

1. Verb-noun names — check_grammar, not process or tool1

2. Descriptions state purpose + inputs + outputs + WHEN to use — so the host routes to the right tool

3. Single-purpose tools — grammar, readability, and rewrite are different jobs, kept separate (not a mode mega-tool)

4. Typed parameters — text: str, tone: str = "professional" auto-generate the JSON input schema

5. Structured output — every tool returns a predictable dict, never free-form prose

How it's built

from mcp.server.fastmcp import FastMCP
mcp = FastMCP("grammar-coach")

@mcp.tool()
def check_grammar(text: str) -> dict:
    """Check English text for grammar, spelling, and style errors. ..."""
    return run_grammar_check(text)

The @mcp.tool() decorator turns a documented, type-hinted Python function into a fully-schema'd MCP tool — name from the function, schema from the type hints, description from the docstring.

Run / test locally

pip install -r requirements.txt
python server.py          # starts the server over stdio

Register it with Claude Desktop by adding the block in claude_desktop_config.example.json to your Claude config, then ask Claude: "Check the grammar of this sentence: ..." — it will call check_grammar.

Architecture

AI Host (Claude Desktop) ──MCP/stdio──► server.py ──► grammar_engine.py ──► LanguageTool
   "check my grammar"                    (3 tools)       (analysis)

Skills demonstrated

MCP server design · Tool schema definition · Structured output · Single-responsibility tool granularity · Python SDK (FastMCP)

License

MIT.