Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add alpacahq/alpaca-skills --skill market-datagit clone --depth 1 https://github.com/alpacahq/alpaca-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/alpacahq/alpaca-skills/market-data)<a href="https://agentmods.dev/skills/alpacahq/alpaca-skills/market-data"><img src="https://agentmods.dev/badge/skills/alpacahq/alpaca-skills/market-data/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/alpacahq/alpaca-skills/market-data"><img src="https://agentmods.dev/badge/skills/alpacahq/alpaca-skills/market-data.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00080 | $0.03022 |
| Opus 5.5 | $0.00032 | $0.01209 |
| Sonnet 5.5 | $0.00016 | $0.00604 |
| Haiku 4.5 | $0.00008 | $0.00302 |
Grade A, and why
alpaca-broker-market-data scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Alpaca Market Data API — Stocks (REST + WebSocket)
Real-time and historical US equity data. Unlike the Broker endpoints, market data lives on its own host with its own auth, and the real-time feed is WebSocket, not SSE.
Read
alpaca-broker-integrationfirst. Assets/clock/calendar live on the Trading API host; everything else here is the Market Data API host.
Reference
- Guides:
https://docs.alpaca.markets/docs/historical-stock-data,https://docs.alpaca.markets/docs/streaming-market-data - Live schema:
alpaca-docsMCP →list-endpointstitle"Market Data API"
0. Hosts & auth
| Surface | Host |
|---|---|
| Market data REST | https://data.alpaca.markets (sandbox data.sandbox.alpaca.markets) |
| Market data WebSocket | wss://stream.data.alpaca.markets/{version}/{feed} |
| Assets / clock / calendar | https://api.alpaca.markets (Trading API) — paper: paper-api.alpaca.markets |
Auth: Broker partners authenticate with a client-credentials access token (POST https://authx.alpaca.markets/v1/oauth2/token — flow in alpaca-broker-integration): send Authorization: Bearer <token> on REST and on the WS handshake, or authenticate over WS with {"action":"auth","key":"access_token","secret":"<token>"} (the literal string access_token is the key). Tokens are valid 15 minutes — cache and refresh one, don't mint per call. Key/secret (APCA-API-* headers, or {"action":"auth","key":"…","secret":"…"} on WS) is the Trading API path and the documented legacy Broker path.
1. REST endpoints
| Path | Purpose |
|---|---|
GET /v2/stocks/snapshots?symbols=… · GET /v2/stocks/{symbol}/snapshot |
Snapshot (latest trade/quote + bars) |
GET /v2/stocks/bars?symbols=… · GET /v2/stocks/{symbol}/bars |
Historical OHLCV bars |
GET /v2/stocks/bars/latest · …/{symbol}/bars/latest |
Latest bar(s) |
GET /v2/stocks/trades[/latest] · GET /v2/stocks/quotes[/latest] |
Historical / latest trades & quotes |
GET /v2/stocks/auctions |
Opening/closing auctions |
GET /v2/stocks/meta/conditions/{trade|quote} · /meta/exchanges |
Code lookups |
GET /v1beta1/news?symbols=… |
News (max limit 50) |
GET /v1beta1/screener/stocks/most-actives · /screener/{stocks|crypto}/movers |
Screeners |
GET /v2/assets (Trading API host) · GET /v1/assets (Broker API host) |
Asset master / tradability |
GET /v2/clock · GET /v2/calendar (Trading API host) |
Market hours |
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 7d ago Changed 5ab38c2f92e1
- 1mo ago First seen · 124 lines · 80 tokens per session scan A f2ab4bc14d49
alpaca-broker-market-data is a skill published in the GitHub repository alpacahq/alpaca-skills (157 stars, last pushed today), licensed Apache-2.0. It adds 80 tokens to every session and 3,022 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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