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Massive Claude Code Plugin
Ship code against the Massive API faster, with fewer hallucinations. This plugin loads Massive's SDK conventions, endpoint catalog, and common failure modes into every Claude Code session, plus five slash commands for the workflows you run most often.
Why
Two problems Claude runs into when you're coding against a real financial data API.
Slow. Every session starts with you explaining that Bitcoin is X:BTCUSD, that list_aggs auto-paginates, that get_rsi returns a single object not an iterator, that crypto endpoints use a different prefix from forex. Minutes burned before any code lands.
Wrong. Claude is confident. It will write list_rsi(...) when the method is get_rsi, pass tickerAnyOf as an array in JS when the SDK wants a comma-separated string, or reach for bar.Open in Go when the actual field is bar.O. You end up debugging hallucinations instead of business logic.
This plugin fixes both. CLAUDE.md teaches the model the right patterns so correct code comes out the first try; the skills wrap the workflows you run most; the MCP server gives Claude a way to inspect real data when you need to validate a response shape or debug a 401.
What ships
API knowledge in .claude/CLAUDE.md
Loaded every session. Covers:
- Ticker prefixes across six asset classes (equities, options, crypto, forex, indices, futures)
- SDK method name maps for Python, JavaScript, Go, and Kotlin (same operations, different names in each)
- Pagination behavior:
list_*auto-paginates,get_*returns single objects,limitis page size not total results - Plan tier gates, so Claude doesn't recommend quotes on Basic or Greeks without Options Starter
- Common 401 / 429 / empty-result debugging patterns
- Rate-limit retry helpers, including the non-obvious detail that the Python SDK's
BadResponsebody matches on text ("maximum requests","rate limit") instead of HTTP status
Five skills
| Command | What it does |
|---|---|
/massive:scaffold my-app rest python | New project with dependencies, .env, and working boilerplate. Python, JS/TS, Go, or Kotlin. Checks plan tier before scaffolding WebSocket or Streamlit projects that need Starter. |
/massive:discover "options Greeks for SPY" | Finds the right endpoint and shows SDK usage in your language. |
/massive:debug | Diagnoses API errors, empty results, and SDK quirks across all four languages. Covers the Python BadResponse rate-limit pattern, Go nil-pointer guards, JS object-param shape, Kotlin JitPack deps. |
/massive:options "iron condor" SPY python | Builds a runnable options strategy as a project. Screens the chain, calculates max profit / max loss / breakeven, ranks by risk-reward. Expiration dates are derived from today, not hardcoded. |
/massive:dashboard my-dash multi-asset | Modular Streamlit dashboard with a cached data layer and Plotly charts. Four focus areas: multi-asset, options, crypto, macro. |
Live API via MCP (optional, installed separately)
The Massive MCP server is a separate install (see Getting started, steps 2-3). Once registered with claude mcp add, Claude gets three tools:
search_endpoints(query): find endpoints by natural-language description.call_api(endpoint, params, store_as): call a REST endpoint and optionally save the response as a DataFrame.query_data(sql): run SQL against stored DataFrames, with built-in financial functions (Black-Scholes, Sharpe, returns, SMA, EMA).
Reach for these when you need to see what an endpoint actually returns before writing code against it, or when something in your code isn't returning what you expected. REST endpoints are polled. Real-time streaming lives on the WebSocket feeds, not in these tools.
Skip the MCP install if you only want knowledge + skills. The plugin still works; you just won't get live-data lookups from inside a session.
Getting started
1. Prereqs
- Claude Code CLI. Check with
claude --version. - uv, to install the Massive MCP server (only needed for live-API features). Check with
uv --version. Install withcurl -LsSf https://astral.sh/uv/install.sh | sh(macOS or Linux),powershell -c "irm https://astral.sh/uv/install.ps1 | iex"(Windows), orpip install uv(any platform). - A Massive API key from massive.com/dashboard. The free Basic tier is enough to start (end-of-day data, 5 calls/min).
For scaffolding in languages other than Python, you'll also need Node.js 16+, Go 1.21+, or JDK 21+ with Gradle, depending on the language you pick. The plugin itself doesn't require these; they only matter when /massive:scaffold creates a project in that language and you want to run it.
