JUjustvugg·Feb 1, 2026Submission
Show HN: PolyMCP – Expose Python/TS functions as MCP tools easily
I built PolyMCP to make it trivial to expose existing functions as MCP tools, without rewriting logic or adding much glue code.
The goal: take “normal” Python or TypeScript functions and instantly make them usable by MCP clients (Claude Desktop, agents, Ollama, etc.).
Python example
from polymcp.polymcp_toolkit import expose_tools
def greet(name: str) -> str:
"""Say hello."""
return f"Hello, {name}!"
def add(a: int, b: int) -> int:
"""Add two numbers."""
return a + b
app = expose_tools([greet, add], title="My MCP Tools")
Run with:
uvicorn server:app --reload
MCP endpoints appear at:
• /mcp/list_tools
• /mcp/invoke
TypeScript example
import { z } from "zod";
import { tool, exposeTools } from "polymcp";
const uppercaseTool = tool({
name: "uppercase",
description: "Convert text to uppercase",
inputSchema: z.object({ t
Read the rest
ext: z.string() }),
function: async ({ text }) => text.toUpperCase(),
});
const app = exposeTools([uppercaseTool], { title: "Text Tools" });
app.listen(3000);
More “real” example (Python)
import pandas as pd
from polymcp.polymcp_toolkit import expose_tools
def calculate_commissions(sales_data: list[dict]):
df = pd.DataFrame(sales_data)
df["commission"] = df["sales_amount"] * 0.05
return df.to_dict(orient="records")
app = expose_tools([calculate_commissions], title="Business Tools")
What you get
• Reuse existing code with minimal changes
• MCP-compatible (Claude Desktop, agents, Ollama, etc.)
• HTTP, stdio, and WASM support
• Automatic input validation
• Basic production features (budgets, retries, redaction, logs)
• Built-in inspector for testing and monitoring
Install
• Python: pip install polymcp
• TypeScript: clone repo → cd polymcp-ts → npm install → npm run build
Repo:
https://github.com/poly-mcp/Polymcp
Curious what kind of function people would expose first if it was this easy.
Feedback very welcome.