How to use
- Copy the installation command and review the source package before installing it in your own agent environment.
- Check the source document for required tools, credentials and supported hosts.
- Describe your input and desired deliverable; review the output against the source material.
npx skills add https://github.com/full-stack-skills/rust-skills --skill rust-crate-discoveryBefore you start
- Installation does not include a model subscription, API allowance or permission to access your files.
- Repository stars and installation counts describe activity, not an independent quality or security test.
Original skill document
Rendered from the source repository. Headings, examples, code, tables, links, and referenced images are preserved.
Rust Crate Discovery and Evaluation
Authority: crates.io API, docs.rs, GitHub REST API, RustSec Advisory Database.
This skill owns the discovery + evaluation phase before a crate enters your Cargo.toml. It uses a bundled Python tool (scripts/crate_eval.py) to fetch signals from 4 sources and produce a weighted 0-100 score with a letter grade (A/B/C/D/F), red-flag list, and a recommendation. It does not own post-adoption governance (rust-dependencies), manifest mechanics (rust-cargo-build), or semver (rust-semver).
Capability Boundaries
✅ Strengths
- Search crates.io by keyword, category, or name — returns ranked candidates
- Evaluate a single crate in depth: fetch metadata from crates.io + docs.rs + GitHub + RustSec
- Compare 2+ crates side-by-side with subscore breakdown
- Score each crate 0-100 across 6 dimensions: adoption (30), maintenance (25), documentation (15), maturity (15), community (10), license (5)
- Flag red concerns: stale, advisories, no docs, low adoption with churn, single-maintainer bus factor, no source repo, license missing
- Recommend the best fit, surfacing blocking concerns before the user adopts
- Output as human-readable report or machine-readable JSON (for agent consumption)
⚠️ Prerequisites
- Network access (the tool fetches from crates.io, docs.rs, GitHub, RustSec)
- Python 3.9+ (no external pip packages — stdlib only)
❌ Out of Scope
- Post-adoption governance (cargo-deny config, license policy, advisory response workflow) →
rust-dependencies - Cargo.toml field semantics →
rust-cargo-build - Semver and breaking-change classification →
rust-semver - Which std type to use instead of a crate →
rust-stdlib
Data Privacy
This skill makes outbound HTTP requests to crates.io, docs.rs, GitHub, and RustSec. The User-Agent identifies the tool. No user data is collected or transmitted beyond the crate name in the URL path (which is public registry data). For private/proprietary crate names, prefer manual review.
The Evaluation Tool — scripts/crate_eval.py
A stdlib-only Python script. Three subcommands:
bash
# Search candidates
python3 scripts/crate_eval.py search "orm"
python3 scripts/crate_eval.py search "http client" --limit 5
python3 scripts/crate_eval.py search "logging" --category "development-tools::debugging"
# Evaluate one crate in depth
python3 scripts/crate_eval.py eval rbatis
python3 scripts/crate_eval.py eval rbatis --json # machine-readable
python3 scripts/crate_eval.py eval rbatis -v # show raw signals
python3 scripts/crate_eval.py eval rbatis --skip-github # faster, less signal
# Compare multiple candidates
python3 scripts/crate_eval.py compare rbatis diesel sea-orm sqlxWorkflow
- Search —
search "<domain keyword>"to surface candidates. Inspect the top 5-10 by downloads and recency. - Shortlist — pick 2-4 names with non-trivial adoption (≥1k downloads) and recent activity.
- Compare —
compare <names...>to get the side-by-side scorecard. - Investigate red flags — for the top pick, read the red-flag list. Block on security advisories; investigate stale or single-maintainer concerns.
- Verify fit — the score measures health, not fitness. Read the crate's docs, check its API shape (
rust-api-designlens), confirm it covers your use case. - Hand off — once adopted, set up
cargo-deny(rust-dependencies) and pin version policy (rust-semver).
Reading the output
=== rbatis === A (92/100) — RECOMMENDED — strong fit, low risk
version 4.9.6 | 657,356 downloads (19,938 recent) | license: Apache-2.0
Subscores:
adoption █████████████░░░░░░░░░░░░ 27/30
maintenance ████████████░░░░░░░░░░░░░ 25/25
...
Red flags:
! license not declared- Grade + score — at-a-glance health
- Subscores — which dimensions are strong/weak
- Notes (
+) — positive signals - Red flags (
!) — concerns to investigate before adopting - Recommendation — verdict (RECOMMENDED / LIKELY SUITABLE / ACCEPTABLE / CAUTION / BLOCK / RISKY)
Scoring Model
| Dimension | Max | What it measures | Key signals |
|---|---|---|---|
| Adoption | 30 | Is anyone using this? | all-time downloads, recent (90-day) downloads |
| Maintenance | 25 | Is it actively maintained? | last crates.io update, version count, GitHub last commit |
| Documentation | 15 | Can users learn it? | docs.rs build, description, docs URL, repo link |
| Maturity | 15 | Is the API stable? | age, stable version ≥1.0, has repo |
| Community | 10 | Is there a contributor base? | GitHub stars, contributors |
| License | 5 | Is it permissive? | permissive (MIT/Apache/BSD) preferred; copyleft penalized |
| Total | 100 |
Grade bands
| Grade | Score | Meaning |
|---|---|---|
| A | ≥85 | Excellent — recommended |
| B | 70-84 | Good — likely suitable |
| C | 55-69 | Acceptable — verify fit |
| D | 40-54 | Risky — investigate before use |
| F | <40 | Avoid — significant concerns |
See references/scoring-rubric.md for the full formula and signal weights.
Red Flags Catalog
The tool surfaces specific concerns. Always read these before adopting.
| Flag | Severity | Action |
|---|---|---|
| RustSec advisory | Block | Pin to fixed version or pick alternative |
| No release in >12 months | High | Check if abandoned; consider fork or alternative |
| Last GitHub commit >6 months | High | Activity may have moved elsewhere |
| No docs.rs build | Medium | API docs may be missing; check manually |
| License not declared | Medium | Treat as proprietary; cannot use without clarification |
| Low adoption with many versions | Medium | Churn without traction; investigate quality |
| Pre-1.0 with 20+ versions | Medium | API likely unstable across minor bumps |
| Single maintainer + low adoption | Medium | Bus factor risk; consider backing up or forking |
| No source repository | High | Cannot audit; avoid |
See references/red-flags.md for the full catalog and decision guidance.
Decision Shortcuts
| Question | Answer |
|---|---|
| Which crate for X? | search "X", then compare top 3-4 |
| Is this crate safe? | eval <name>; check red flags for advisories |
| Is it maintained? | eval <name>; check maintenance subscore + last update |
| Is the API stable? | eval <name>; check maturity subscore + version ≥1.0 |
| What's the license? | eval <name>; appears in signals |
| A vs B vs C? | compare A B C; pick highest score without blocking red flags |
| Score says A but it doesn't fit my use case | Trust the fit check over the score — score measures health, not fitness |
When the score is misleading
- Niche crates — a domain-specific crate may have low downloads but be the only option. Score will understate; rely on manual review.
- New crates — recent releases have low adoption signals; check maintainer track record instead.
- Forks — a fork may have few downloads but be the maintained successor. Check the parent crate's status.
- Internal/private crates — not on crates.io; this tool won't help. Use manual review.
Resources
- Scoring Rubric — full formula, log-scale parameters, subscore breakdowns
- Red Flags Catalog — full flag list with severity and action
- API Endpoints Reference — the 4 data sources and their endpoints
- Evaluation Workflow Examples — worked scenarios (ORM choice, HTTP client, logging)
- `scripts/crate_eval.py` — the evaluation tool (run with
python3)
Upstream Sources
- crates.io API — search, crate metadata, version downloads
- docs.rs — documentation build status, version presence
- GitHub REST API — stars, contributors, last commit, open issues
- RustSec Advisory Database — known vulnerabilities
- crates.io-index — registry index (alternative to API)
