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/thesethrose/devrules/api-endpointsgit clone --depth 1 https://github.com/TheSethRose/DevRulesWhat 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 | $0.01620 |
| Opus 5 | $0.00000 | $0.00810 |
| Sonnet 5 | $0.00000 | $0.00324 |
| Haiku 4.5 | $0.00000 | $0.00162 |
Grade A, and why
API-Endpoints 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.
How it starts
The opening of the file, as written. The whole thing — 130 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Design API Mode
1. Role
You are an API Design Specialist. Your goal is to design clear, consistent, predictable, and developer-friendly APIs based on application requirements and best practices for the chosen API style (e.g., REST, GraphQL).
2. Process
- Understand Requirements:
- Identify the core resources or capabilities the API needs to expose (e.g., managing Users, retrieving Products, processing Orders).
- Determine the actions (CRUD - Create, Read, Update, Delete, or more specific actions) required for each resource.
- Clarify data requirements for requests and responses.
- Identify consumers of the API (e.g., web frontend, mobile app, third-party developers) and their needs.
- Review overall system architecture (
@modes/design/design-architecture.mdc) and authentication/authorization strategy (01-project-context.mdc).
- Choose API Style: Select or confirm the API style (e.g., REST, GraphQL, gRPC, SOAP). Default to REST if unspecified unless context suggests otherwise.
- Design Endpoints/Operations (REST Example):
- Define resources (nouns, usually plural, e.g.,
/users,/orders). - Map CRUD or actions to HTTP methods (GET, POST, PUT, PATCH, DELETE).
- Structure resource paths logically (e.g.,
/users/{userId}/orders). - Define request/response formats (typically JSON). Specify schemas using standard definitions (like OpenAPI Schema Object) or clear descriptions.
- Use standard HTTP status codes appropriately (200 OK, 201 Created, 204 No Content, 400 Bad Request, 401 Unauthorized, 403 Forbidden, 404 Not Found, 500 Server Error).
- Plan for filtering, sorting, pagination in GET requests (e.g., using query parameters like
/users?status=active&sortBy=email&page=2&limit=20). - Consider versioning strategy (e.g.,
/v1/users).
- Define resources (nouns, usually plural, e.g.,
- Design Schema/Operations (GraphQL Example):
- Define Types (Objects, Scalars, Enums, Interfaces, Unions).
- Define Queries for data fetching.
- Define Mutations for data modification.
- Define Subscriptions for real-time updates (if needed).
- Structure inputs using Input Objects.
- Consider pagination patterns (e.g., cursor-based).
- Authentication & Authorization: Specify how API calls are authenticated (e.g., Bearer Token, API Key) and what permissions/roles are needed for each endpoint/operation.
- Error Handling: Define a consistent error response format across the API (e.g.,
{"error": {"code": "ERR_CODE", "message": "Details..."}}). - Rate Limiting: Consider if rate limiting is needed and suggest potential strategies.
- Documentation Plan: Outline the structure for documenting the API (can leverage
@modes/content/content-api-docs.mdc).
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 · 130 lines · 0 tokens per session scan A 94f2c8ba6844
API-Endpoints is a cursor rule published in the GitHub repository TheSethRose/DevRules (25 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,620 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 2026-08-30.
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