Quantdata Plugin MCP Server

Quant Data — market-statistics skills for AI agents

Measured market statistics for index futures and equities, packaged so an AI agent can use them and — more importantly — report them honestly. Installs natively into Claude Code (plugin), Codex CLI (plugin marketplace) and Gemini CLI (extension), all from this one repository.

The honest summary of what you get: measured edges of 52–56%, published together with the places the models fail. There is a section below on exactly that, and it is not buried.

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Install

Claude Code

/plugin marketplace add celineycn/quantdata-plugin
/plugin install quantdata@quantdata

Codex CLI

The same repository doubles as a Codex plugin marketplace:

codex plugin marketplace add celineycn/quantdata-plugin
codex plugin add quantdata@quantdata

Any other MCP client (Claude Desktop, ChatGPT, Cursor, VS Code, Zed)

The same four endpoints are a remote MCP server. Nothing to install — point the client at:

https://api.quantdata.uk/mcp

Streamable HTTP, and no authentication to try it: it answers on the daily keyless allowance and returns the same complete responses a subscriber gets. Send X-API-Key: qd_... as a header to lift the limit. A stdio bridge ships in quantdata/mcp/ for clients that can only launch a local command; it forwards to the same URL.

Details: quantdata/mcp/README.md.

Gemini CLI

The repository is also a Gemini CLI extension. GEMINI.md carries the three skill bodies merged into one context file:

gemini extensions install https://github.com/celineycn/quantdata-plugin

Then

Start a new session. You do not invoke a skill by name — just ask:

What kind of day is NVDA having?

Is the pullback in ES=F happening on low volume?

Where is max pain for TSLA this Friday?

Which way is dealer gamma leaning on NVDA?

To check it loaded, ask: "Which Quant Data skills do you have?"

Without the plugin system

A skill is just a folder with a SKILL.md in it, so you can also copy them by hand:

mkdir -p ~/.claude/skills
cp -R quantdata/skills/* ~/.claude/skills/

Or project-scoped, committed alongside your code, in .claude/skills/.

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Try it before paying anything

The free tier is the Max Pain and GEX pages. No key, no account, no card:

https://quantdata.uk/max-pain/nvda
https://quantdata.uk/gex/nvda

Max pain (the option strike at which option buyers lose the most in aggregate at expiration), put/call ratio and open interest by expiration, one page per US individual stock, rebuilt nightly — and a separate GEX page per ticker with net gamma exposure and the zero gamma (flip) level. Lowercase tickers. https://quantdata.uk/max-pain and https://quantdata.uk/gex are the coverage lists.

To check the research before paying for it, read https://quantdata.uk/methodology — an ordinary web page, free, no key. It publishes the fact-check of the trading literature's famous probability claims against 3,946 S&P 500 futures trading days (2010–2026). The claim that one of the session's extremes forms within the first 90 minutes is usually taught as 90%; the measured figure is 81.2%. The pattern holds across every claim tested — directionally right, inflated by roughly 7–10 percentage points.

Start there. If the numbers are not the size you expected from an honest test, do not buy.

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The paid endpoints

Every endpoint below answers 10 calls a day with no key at all — the same complete response a subscriber gets, not a trimmed sample. Install the plugin, ask a question, and you will get a real answer before anyone asks you for a card. A key removes the daily limit.

One plan: $39/month, first 3 days free. Checkout is self-serve at https://quantdata.uk/pricing, a card is collected up front, and the key is shown immediately on the page Stripe returns you to. Cancel any time from the Stripe receipt.

One key covers all four. The two options endpoints are deliberately separate because the two figures are not equally reliable: max pain is arithmetic anyone can reproduce from the same chain, gamma is a Black-Scholes estimate built on an unobservable dealer-positioning convention. The skills quote the first as a figure and the second as an estimate.

The fact-check verdicts live on https://quantdata.uk/methodology as a static table — a web page to read, free and needing no key, not an endpoint to call.

Keys bought under the older two-product pricing keep working at their original price.

An AI agent cannot buy this for you. Card authentication (3-D Secure) requires the cardholder, so the skills are written to hand you the link and stop rather than attempt a purchase. That is deliberate.

Set your key

Never paste a key into SKILL.md — those files are meant to be copied, committed and shared.

# ~/.zshrc (macOS default) or ~/.bashrc
export QUANTDATA_API_KEY="qd_your_key_here"

Then open a new terminal, or run source ~/.zshrc. Check it:

curl -s -H "X-API-Key: $QUANTDATA_API_KEY" https://api.quantdata.uk/v1/brooks/SPY

For an agent with no shell, the key goes wherever that tool stores secrets — an Actions authentication field, a credential entry, a .env loaded by your runtime. Same rule: a secret store, not a shared file.

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Using these on platforms with no plugin system

Nothing here is specific to any one agent. A SKILL.md body is instructions plus an HTTP contract, so it works anywhere you can set a system prompt and send a request with a custom header. (Claude Code, Codex and Gemini CLI install natively — see Install above.)

1. Open the SKILL.md you want, under quantdata/skills/.
2. Copy everything below the closing --- of the YAML header.
3. Paste it into your agent's system prompt, custom instructions or persona field.
4. Replace the $QUANTDATA_API_KEY references with whatever your platform calls its secret.

Known to work this way: ChatGPT Custom GPTs (paste into Instructions, and add api.quantdata.uk as an Action with an X-API-Key header), Cursor and Windsurf rules files, Cline, GitHub Copilot instructions, n8n and Dify agent nodes, CrewAI and AutoGen agent backstories, LangChain system messages, and anything built directly on the OpenAI or Anthropic SDKs.

If your tool can send one HTTP request with one custom header, it is supported. There is no SDK, no OAuth flow and no callback URL.

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What every one of these skills enforces

These rules are written into each SKILL.md and they are the reason the plugin exists:

• Never present output as a buy or sell recommendation. The API returns a probability distribution and historical frequencies. It does not know your position, account or risk. Turning "TrendUp 0.34" into "go long" is the agent inventing advice.
• Always carry the disclaimer. Every response has a disclaimer field; it travels with the numbers.
• Never claim precision the numbers do not have. The honest win rates are 52–56%. An agent that rounds that into "strong signal" has broken the product.
• Name the baseline. 66% top-1 accuracy is meaningless until you also say the majority-class baseline is 37%.
• Flag out-of-distribution use. The day-type model was trained on S&P 500 E-mini futures. A read on a single stock, on gold, or on crypto is descriptive, not validated.
• At a paywall, relay message_for_your_human and stop. Never retry a 402, and never substitute a different data source and present the result as Quant Data output.

Where this does not work

Publishing this is the point, not a disclaimer:

• Crypto and gold have a consistent anti-signature. Of eight pre-registered Bitcoin signals, zero confirmed, and no_supply reversed direction outright.
• Chart patterns did not survive testing. Over 121,000 pattern detections produced an AUC of 0.54 — near a coin flip.
• The Asian session did not transfer. The pre-registered test of day-type gating on the Asian session returned NO_GO.

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Educational analytics and developer tooling. Not investment advice, not a recommendation to buy or sell, not a price forecast. Trading involves risk of loss; past performance does not guarantee future results. Independent research — not affiliated with or endorsed by Al Brooks, David Weis, or any exchange or broker.

Docs: https://quantdata.uk/skills · Questions: quantdata@agentmail.to