may6-mcp

Local MCP server that exposes the may6 financial-data API as four Claude-Desktop-compatible tools. Drop it into your Claude Desktop config and Claude can search instruments, look up identifiers, pull EOD price history, and read SEC EDGAR fundamentals — without writing any API integration code.

This is a thin protocol adapter: caching, quota tracking, source attribution, BYO-key handling, and error classification all happen on the may6 backend. The MCP server just translates MCP tool calls into HTTPS requests and shapes responses for agent consumption.

Install

You don't need to install anything ahead of time — npx runs the latest published version on demand:

npx -y @may6/mcp-server

If you'd rather have it on your PATH for direct invocation:

npm install -g @may6/mcp-server
may6-mcp

Requires Node.js 20 or later.

Claude Desktop config

Add an entry under mcpServers in your claude_desktop_config.json.

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
• Windows: %APPDATA%\Claude\claude_desktop_config.json

Minimal config (uses may6's hosted API with no BYO keys):

{
  "mcpServers": {
    "may6": {
      "command": "npx",
      "args": ["-y", "@may6/mcp-server"]
    }
  }
}

BYO-key config (forwards your own provider keys to may6 so usage doesn't draw from may6's shared quota):

{
  "mcpServers": {
    "may6": {
      "command": "npx",
      "args": ["-y", "@may6/mcp-server"],
      "env": {
        "MAY6_TWELVE_DATA_KEY": "your-twelve-data-key-here"
      }
    }
  }
}

Restart Claude Desktop after editing the config. You should then see "may6" in the tools menu of the chat.

Tools

| Tool | What it does | |---|---| | search_instruments | Free-text search by company name or partial ticker. Returns matches with FIGIs, exchange, country, currency, security type. Use when the user mentions a company name and you don't have a ticker yet. | | get_instrument | Detailed instrument lookup by ticker — all identifiers (FIGI, ISIN, CIK, etc.) and listings across exchanges. Use after search_instruments, or when the user provides a ticker directly. | | get_prices_eod | Daily end-of-day price history (open/high/low/close/volume per trading day). Defaults to the last year. Use for charts, return calculations, price analysis. | | get_fundamentals | SEC EDGAR XBRL fundamentals for US-listed companies (revenue, net income, etc.). Optional concept filter for a single XBRL line item. Use for financial analysis and ratio calculations. |

Configuration

All configuration is via environment variables. Set them in your Claude Desktop config's env block, or export them in your shell when running locally.

| Variable | Purpose | |---|---| | MAY6_API_BASE_URL | Override the may6 API base URL. Defaults to https://may6.vercel.app. | | MAY6_TWELVE_DATA_KEY | BYO Twelve Data API key. Forwarded as X-Provider-Key-Twelve-Data. | | MAY6_POLYGON_KEY | BYO Polygon API key. Forwarded as X-Provider-Key-Polygon. | | MAY6_FMP_KEY | BYO Financial Modeling Prep key. Forwarded as X-Provider-Key-Fmp. | | MAY6_TIINGO_KEY | BYO Tiingo key. Forwarded as X-Provider-Key-Tiingo. | | MAY6_ALPHA_VANTAGE_KEY | BYO Alpha Vantage key. Forwarded as X-Provider-Key-Alpha-Vantage. | | MAY6_ALPACA_KEY | BYO Alpaca key. Forwarded as X-Provider-Key-Alpaca. | | MAY6_EODHD_KEY | BYO EODHD key. Forwarded as X-Provider-Key-Eodhd. | | MAY6_MCP_DEBUG | Set to 1 to log every constructed URL and response status to stderr. |

Troubleshooting

Claude Desktop doesn't see the server. Confirm the config file is valid JSON (a single trailing comma will silently break it), then fully quit and relaunch Claude Desktop — reloading the window is not enough.

Tools show up but every call fails. Try MAY6_MCP_DEBUG=1 and run may6-mcp from a terminal. The debug logs go to stderr and show the exact URL and response status for every request.

BYO-key env var doesn't appear to take effect. Env vars set in the Claude Desktop config only apply on the next launch. Quit and relaunch Claude Desktop after editing.

npx complains about cached versions. npx -y @may6/mcp-server@latest forces the resolver to skip the cache.

Releasing

Build artifacts in dist/ are produced by npm run build. The npm prepublishOnly hook will rebuild before any publish.

npm version patch       # or minor/major
npm publish

publishConfig.access is set to public in package.json so scoped publishes don't require the --access public flag on the command line. The executable installed by the package is may6-mcp regardless of the package name.

License

MIT.