Polygon.io MCP Server
OfficialOfficial Polygon.io server with tools for stocks, options, forex, and crypto market data.
Add to your client
Copy the config for your MCP client and paste it into its config file.
uvx --from git+https://github.com/polygon-io/mcp_polygon@v0.4.0 mcp_polygonPaste into ~/Library/Application Support/Claude/claude_desktop_config.json
{
"mcpServers": {
"polygon-io-mcp-server": {
"command": "uvx",
"args": [
"--from",
"git+https://github.com/polygon-io/mcp_polygon@v0.4.0",
"mcp_polygon"
],
"env": {
"POLYGON_API_KEY": "<your-polygon-api-key>"
}
}
}
}Requires `uv` (the Python package runner). Install it from https://docs.astral.sh/uv/ if `uvx` is not found.
Before you start
- A Massive.com (formerly Polygon.io) API key from massive.com — set as MASSIVE_API_KEY (legacy POLYGON_API_KEY also accepted)
- Python 3.12 or higher
- Astral uv 0.4.0+ to install and run the server
About Polygon.io MCP Server
This is the official MCP server for Polygon.io's financial market data — note that Polygon.io rebranded to Massive.com on October 30, 2025, so the package is now published as mcp_massive (repo: github.com/massive-com/mcp_massive). Existing Polygon API keys, accounts, and the api.polygon.io base continue to work, and POLYGON_API_KEY is still accepted as a deprecated alias for MASSIVE_API_KEY.
Rather than exposing one tool per REST endpoint, the server uses a composable three-tool design: search_endpoints to discover the right API by natural language, call_api to execute any Massive/Polygon REST endpoint (optionally storing the response), and query_data to run SQL over stored results. This keeps the tool count small while covering stocks, options, forex, crypto, and futures. Built-in helper functions add options Greeks (Black-Scholes delta/gamma/theta/vega/rho), returns, moving averages, and ratios.
It runs locally over stdio by default (SSE and streamable-HTTP are also configurable) and is installed with uv. Use it when you want full programmatic access to Polygon/Massive market data inside an agent without hand-coding a client for each endpoint.
Tools & capabilities (4)
search_endpointsDiscover the right Massive/Polygon REST endpoints and built-in functions from a natural-language query.
call_apiExecute any Massive/Polygon REST endpoint, with optional storage of the response into a local SQLite database.
query_dataRun SQL queries against data previously stored by call_api.
Built-in functions (Black-Scholes Greeks, returns, moving averages, ratios)Analytics helpers callable through the API layer — e.g. options delta/gamma/theta/vega/rho and return calculations.
When to use it
- Use it when you want an agent to reach any Polygon/Massive endpoint (stocks, options, forex, crypto, futures) without per-endpoint tooling.
- Use it when you need to store API responses and then run SQL analysis over them via query_data.
- Use it when computing options Greeks or returns from the built-in financial functions.
- Use it when you have an existing Polygon.io API key and want to keep using it after the Massive rebrand.
- Use it when you want a small, discoverable tool surface (search → call → query) instead of dozens of tools.
Quick setup
- 1Get an API key from massive.com (existing polygon.io keys still work).
- 2Install uv, then run: uv tool install "mcp_massive @ git+https://github.com/massive-com/mcp_massive@v0.10.0".
- 3For Claude Code: claude mcp add massive -e MASSIVE_API_KEY=your_key -- <binary path>.
- 4For Claude Desktop: add the server entry with the binary path and MASSIVE_API_KEY to claude_desktop_config.json.
- 5Restart your MCP client and verify with a search_endpoints query.
Security notes
Read-only market data with no trading capability; keep POLYGON_API_KEY in env. Pin the git tag (e.g. @v0.4.0) rather than tracking main so you run reviewed code.
Polygon.io MCP Server FAQ
Why does the package say Massive.com instead of Polygon.io?
Polygon.io rebranded to Massive.com on Oct 30, 2025. The repo and package moved to massive-com/mcp_massive, but it is the same official server and data.
Does my existing Polygon API key still work?
Yes. Existing keys, accounts, and api.polygon.io continue to work, and POLYGON_API_KEY is accepted as a deprecated alias for MASSIVE_API_KEY.
Why only three tools?
The server uses a composable design — search_endpoints, call_api, and query_data — that together cover the entire REST API surface instead of one tool per endpoint.
What transport does it use?
stdio by default; SSE and streamable-HTTP can be selected via the MCP_TRANSPORT environment variable or --transport flag.
What runtime do I need?
Python 3.12+ and Astral uv 0.4.0+.
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