api-conventions

A set of rules for designing API endpoints, which are web addresses that software uses to exchange data. It requires a shared response shape and input checks at the endpoint boundary.

In plain words
What is it for?
Use it when adding or reviewing endpoints that return data or errors. It also guides where and how to validate incoming values with Zod.
Why use it?
It keeps API responses consistent and catches invalid input before it reaches application logic. This makes clients easier to write and reduces repeated decisions across endpoints.

Cursor rule for Cursor

Install

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.

agentmods
npx agentmods add rules/ahnafyy/skills-evals/api-conventions
Clone the repo
git clone --depth 1 https://github.com/ahnafyy/skills-evals

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 39 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.00039
Opus 5 $0.00000 $0.00019
Sonnet 5 $0.00000 $0.00008
Haiku 4.5 $0.00000 $0.00004

Measured 2d ago against content hash 5427939994e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

api-conventions 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 2d 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.

test/fixtures/sample-repo/.cursor/rules/api-conventions.mdc · 8 lines

What it actually says

All endpoints return { data, error } envelopes. Validate input with zod at the boundary.

Changes

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.

  1. 2d ago First seen · 8 lines · 0 tokens per session scan A 5427939994e5

Subscribe to this mod's changes

api-conventions is a cursor rule published in the GitHub repository ahnafyy/skills-evals (3 stars, last pushed 1mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 39 tokens. 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.