# Apilookup

> Use when work depends on current external API behavior, SDK docs, framework versions, breaking changes, migration guides, changelogs, release notes, deprecations, or syntax that may have changed.

- **Type:** Skill
- **Install:** `agentstack add skill-cofin-flow-apilookup`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [cofin](https://agentstack.voostack.com/s/cofin)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** Apache-2.0
- **Upstream author:** [cofin](https://github.com/cofin)
- **Source:** https://github.com/cofin/flow/tree/main/skills/apilookup

## Install

```sh
agentstack add skill-cofin-flow-apilookup
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# API Lookup Skill

Look up API documentation, SDK references, library versions, and migration guides using a three-tier resolution strategy that starts with local Flow skill references and escalates to targeted web searches only when needed.

## Overview

Three tiers of resolution, applied in order:

1. **Local skill references** — if a matching Flow skill exists and the registry entry is fresh ( 30 days) or the query needs more, use the registry's known URLs for targeted searches (max 2-4).
3. **Arbitrary lookup** — for technologies without a matching skill, broad web search with a version-first strategy (max 2-4 searches).

## Usage Patterns

Example queries this skill handles:

- "What's the latest Litestar version and what changed?"
- "How do I use React Server Components?"
- "Show me the SQLAlchemy 2.0 migration guide"
- "What breaking changes are in Angular 19?"
- "What's the current Go module proxy API?" (arbitrary — no local skill)
- "Check if there's a newer version of Tailwind CSS"

## How It Works

### Version Registry

`references/registry.json` maps every Flow skill to:

- Current known version and last-checked date
- Package registry (PyPI, npm, crates.io, etc.)
- Official docs URL, changelog URL, and GitHub repo
- Search hint keywords for targeted queries

### Staleness Thresholds

| Age of registry entry | Action |
|-----------------------|--------|
|  90 days | Treat as potentially outdated, do full version check |

### Search Budget

All web lookups are capped at **2-4 searches max**. Prefer `WebFetch` on known URLs over `WebSearch` when registry URLs are available — it is faster and more precise.

## Lookup Rules

See `references/lookup-strategy.md` for the full decision tree. Key principles:

1. **Always start local** — check the registry and load matching skill refs if fresh
2. **Be targeted** — use registry URLs and package names for precise queries
3. **Respect the budget** — 2-4 searches max, stop once you have an authoritative answer
4. **Cite sources** — always include links to official docs or changelogs
5. **Note version gaps** — if local refs cover version X but the current release is Y, tell the user explicitly

## References Index

- **[Lookup Strategy](references/lookup-strategy.md)** — Detailed three-tier resolution instructions
- **[Version Registry](references/registry.json)** — Package metadata and staleness tracking for all skills
- **[Registry Schema](references/registry-schema.md)** — Documents the registry JSON format and fields

## Validation Checkpoint

Before delivering an answer based on an API lookup, verify:

- [ ] **Staleness check** was performed against `registry.json` for known skills
- [ ] **Tier 1 (Local)** was tried first for fresh entries (

## Example: Looking up React Server Components

**Query:** "How do I use React Server Components in Next.js?"

1. **Identify Tech:** React, Next.js.
2. **Check Registry:** Matches `react` skill. `last_checked` is 45 days ago (Tier 2).
3. **Execute Tier 2:**
   - **Step 1 (Version):** WebFetch `https://github.com/facebook/react/releases` -> React 19 is latest.
   - **Step 2 (Specific):** WebSearch `site:nextjs.org react server components pattern 2026`.
4. **Synthesize:**
   - "Based on Next.js 15+ documentation (compatible with React 19):"
   - Explain `use client` vs default server components.
   - Provide code example of a Server Component fetching data.
   - **Citations:** [Next.js RSC Docs](https://nextjs.org/docs/app/building-your-application/rendering/server-components), [React 19 Upgrade Guide](https://react.dev/blog/2024/12/05/react-19).

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [cofin](https://github.com/cofin)
- **Source:** [cofin/flow](https://github.com/cofin/flow)
- **License:** Apache-2.0

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-cofin-flow-apilookup
- Seller: https://agentstack.voostack.com/s/cofin
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.