massive-mcp

An MCP (Model Context Protocol) server that exposes the Massive.com REST Stocks API to Claude Desktop and Claude Code.

Built with FastMCP + httpx (async). Stdio transport.

What it covers

Defaults are tuned to keep responses small (low limit, truncation at 200 items with a _truncated_note). All paginated tools accept cursor and surface next_cursor when more data is available.

Install

# Recommended: uv
uv tool install --from . massive-mcp
# or pipx
pipx install .

For development:

uv sync --extra dev
uv run pytest

Configure

Set your API key via env. Both auth modes are supported — start with bearer; if Massive rejects with 401, switch to query.

export MASSIVE_API_KEY=sk_live_...
export MASSIVE_AUTH_MODE=bearer   # or "query"

Or copy .env.example to .env.

Wire it up

Claude Desktop

Edit claude_desktop_config.json:

• macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

• Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "massive": {
      "command": "uvx",
      "args": ["massive-mcp"],
      "env": {
        "MASSIVE_API_KEY": "sk_live_...",
        "MASSIVE_AUTH_MODE": "bearer"
      }
    }
  }
}

Restart Claude Desktop.

Claude Code

claude mcp add massive --env MASSIVE_API_KEY=sk_live_... --env MASSIVE_AUTH_MODE=bearer -- uvx massive-mcp

Local dev

uv run massive-mcp

Use the MCP Inspector to exercise tools manually:

npx @modelcontextprotocol/inspector uvx massive-mcp

Try it

Once wired up, ask Claude things like:

• "What was NVDA's previous close?"

• "Pull AAPL dividends from the last 12 months."

• "Show me the top 10 gainers right now."

• "Get 5-minute bars for TSLA from yesterday."

• "RSI for SPY over the last 30 days."

Companion skill

This repo also ships a Claude skill — massive-trade-analysis — that uses the MCP tools to produce professional swing / long-term trade plans (entry, SL, cascaded TPs, R:R, position sizing). See skills/ for install instructions.

Notes & limitations

• REST only. No WebSocket / FlatFiles support.

• Stocks asset class only. Options/FX/Crypto endpoints are out of scope for v1.

• Some endpoints (/vX/...) are versioned by Massive as beta — paths may shift.

• 429 responses are auto-retried honoring Retry-After. 5xx are retried with exponential backoff (max 3 attempts).

• API key never logged. Errors strip apiKey from the surfaced URL.

License

MIT