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 agentmods add skills/tommymorgan/claude-plugins/rest-api-guidelinesnpx skills add tommymorgan/claude-plugins --skill rest-api-guidelinesgit clone --depth 1 https://github.com/tommymorgan/claude-pluginsWrote 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/tommymorgan/claude-plugins/rest-api-guidelines)<a href="https://agentmods.dev/skills/tommymorgan/claude-plugins/rest-api-guidelines"><img src="https://agentmods.dev/badge/skills/tommymorgan/claude-plugins/rest-api-guidelines.svg" alt="Measured on agentmods" height="20"></a>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 | $0.00040 | $0.03319 |
| Opus 5 | $0.00020 | $0.01659 |
| Sonnet 5 | $0.00008 | $0.00664 |
| Haiku 4.5 | $0.00004 | $0.00332 |
Grade A, and why
rest-api-guidelines 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 4d 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 — 450 lines — stays where its author put it; the contents beside it link to each section on GitHub.
REST API Design Guidelines
Opinionated guidance for designing consistent, developer-friendly REST APIs. Apply these guidelines when designing new APIs or reviewing existing API designs.
URL Structure
Pattern: /{serviceRoot}/{collection}/{id}
URLs should be human-readable and hierarchical:
https://api.example.com/v1/people/[email protected]/inboxhttps://api.example.com/v1/orders/12345/items
Rules:
- Collection names: unabbreviated, pluralized nouns (
/users,/orders,/messages) - Use path segments for hierarchy, not query parameters
- Keep URLs short and predictable
- Resources that can move or rename should expose stable identifier URLs
URL length: Design for under 2,083 characters to accommodate all clients.
HTTP Methods
| Method | Purpose | Idempotent | Key Rules |
|---|---|---|---|
| GET | Retrieve resource | Yes | Safe, cacheable, no side effects |
| POST | Create resource or submit command | No | Return 201 Created with Location header |
| PUT | Replace entire resource | Yes | Full replacement — unspecified properties are removed |
| PATCH | Partial update | No | Preferred over PUT for updates; supports UPSERT |
| DELETE | Remove resource | Yes | Return 204 No Content |
| HEAD | Metadata only (no body) | Yes | Same as GET without response body |
| OPTIONS | Discover capabilities | Yes | Return Allow header listing supported methods |
PATCH for UPSERT:
- Without precondition headers: service determines create vs. update
- With
If-Match: update only (409 if missing) - With
If-None-Match: *: create only (409 if exists)
Status Codes
Success
| Code | Meaning | Use When |
|---|---|---|
| 200 | OK | Standard success with response body |
| 201 | Created | Resource created; include Location header |
| 202 | Accepted | Long-running operation initiated |
| 204 | No Content | Success with no response body (DELETE, some updates) |
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.
- 4d ago First seen · 450 lines · 40 tokens per session scan A f8daf19e4c9c
rest-api-guidelines is a skill published in the GitHub repository tommymorgan/claude-plugins (4 stars, last pushed 1mo ago), licensed MIT. It adds 40 tokens to every session and 3,319 once invoked, about $0.0002 per session on Opus 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 2026-08-31.
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