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 infraspecdev/tesseract --skill api-design-reviewgit clone --depth 1 https://github.com/infraspecdev/tesseractWrote 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/infraspecdev/tesseract/api-design-review)<a href="https://agentmods.dev/skills/infraspecdev/tesseract/api-design-review"><img src="https://agentmods.dev/badge/skills/infraspecdev/tesseract/api-design-review/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/infraspecdev/tesseract/api-design-review"><img src="https://agentmods.dev/badge/skills/infraspecdev/tesseract/api-design-review.svg" alt="Reviewed on agentmods" width="80" 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 5.1 | $0.00052 | $0.01126 |
| Opus 5.5 | $0.00021 | $0.00450 |
| Sonnet 5.5 | $0.00010 | $0.00225 |
| Haiku 4.5 | $0.00005 | $0.00113 |
Grade A, and why
backend-api-design-review 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 1mo 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 — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Backend API Design Review
Overview
Review HTTP/REST and GraphQL APIs against established conventions: resource-oriented URIs, correct HTTP method semantics, accurate status codes, idempotency where required, consistent error response shape, versioning strategy, and pagination on list endpoints.
The skill is framework-agnostic — applies equally to Spring @RestController, Express routes, FastAPI path operations, Gin handlers, etc.
When to Use
- Reviewing controllers, route handlers, GraphQL resolvers
- Designing a new endpoint during planning
- Auditing API contract changes for backwards compatibility
When NOT to Use
- Internal RPC between services using non-HTTP transports — different conventions
- Async messaging (Kafka, SQS) — separate review concern
- Static asset serving — no API design surface
Review Process
- Inventory all endpoints in scope (HTTP method + path + handler)
- For each endpoint, walk through Evaluation Points A1–A10
- Group findings by endpoint in the output
- Note cross-endpoint inconsistencies (e.g., error shape varies between handlers)
Evaluation Points
| # | Check | What to Look For | Severity |
|---|---|---|---|
| A1 | Resource-oriented URIs | Nouns, not verbs (/users not /getUsers//createUser). Hierarchies via path segments |
Medium |
| A2 | HTTP method semantics | GET = safe + idempotent; POST = create / non-idempotent; PUT = full replace + idempotent; PATCH = partial; DELETE = remove | High |
| A3 | Status code accuracy | 200 only on success with body; 201 on resource creation with Location; 204 on success with no body; 4xx for client error; 5xx for server error. Wrong 2xx family (e.g. 200 vs 204) is Low; masking errors with 200 (e.g. returning 200 for a not-found) is High |
High / Low |
| A4 | Idempotency | PUT and DELETE must be idempotent. POST may use idempotency keys for retried clients | High |
| A5 | Error response consistency | Single shape across all handlers (e.g., { "error": { "code", "message", "details" } }). No mixing { error: "..." } and structured shapes |
Medium |
| A6 | Versioning strategy | URI version (/v1/...), header version, or content negotiation. No unversioned public APIs |
Medium |
| A7 | Pagination | List endpoints support pagination (offset/limit, cursor, page tokens). Documented limits | Medium |
| A8 | Filtering & sorting | Standard query parameter conventions; no exposing DB query syntax raw | Low |
| A9 | Validation surface | Input validated at the boundary (annotations, schema validators); validation errors return 4xx with field details | Medium |
| A10 | Resource representation consistency | Same resource has same fields across endpoints. No selective field hiding without explicit projection params | Medium |
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.
- 1mo ago First seen · 80 lines · 52 tokens per session scan A 0590fbbad281
backend-api-design-review is a skill published in the GitHub repository infraspecdev/tesseract (5 stars, last pushed 3mo ago), licensed MIT. It adds 52 tokens to every session and 1,126 once invoked, about $0.0002 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 2026-09-03.
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