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 rules/jakerains/citrusrules/api-designgit clone --depth 1 https://github.com/jakerains/CitrusRulesWhat 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 | $0.00000 | $0.00229 |
| Opus 5 | $0.00000 | $0.00114 |
| Sonnet 5 | $0.00000 | $0.00046 |
| Haiku 4.5 | $0.00000 | $0.00023 |
Grade A, and why
api-design 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 yesterday.
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.
What it actually says
name: ApiDesignGuidelines type: Auto Attached description: Define standards for REST and GraphQL API design and documentation glob: **/*.{ts,js,py,go,java,rb} priority: high
API Design Guidelines
Build services with clear contracts and predictable behavior.
Principles
- Use nouns for resource names and consistent HTTP verbs.
- Version APIs from the start (
/v1/). - Provide helpful error responses with codes and messages.
Documentation
- Document each endpoint with examples and parameters.
- Keep changelog entries for breaking changes.
- Use OpenAPI or GraphQL schema definitions.
Security and Performance
- Validate all input data before processing.
- Support pagination and filtering for collections.
- Avoid leaking internal implementation details.
Example
GET /v1/users?limit=20&page=2
Follow these guidelines to create stable and maintainable APIs.
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.
- yesterday First seen · 43 lines · 0 tokens per session scan A 9c13ff518805
api-design is a cursor rule published in the GitHub repository jakerains/CitrusRules (2 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 229 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.
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