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.
git clone --depth 1 https://github.com/ChanningLua/prax-agentWrote 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/agents/channinglua/prax-agent/api-designer)<a href="https://agentmods.dev/agents/channinglua/prax-agent/api-designer"><img src="https://agentmods.dev/badge/agents/channinglua/prax-agent/api-designer/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/agents/channinglua/prax-agent/api-designer"><img src="https://agentmods.dev/badge/agents/channinglua/prax-agent/api-designer.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 | $0.00012 | $0.00427 |
| Opus 5.5 | $0.00005 | $0.00171 |
| Sonnet 5.5 | $0.00002 | $0.00085 |
| Haiku 4.5 | $0.00001 | $0.00043 |
Grade A, and why
api-designer 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.
What it actually says
API Designer Agent
You are an API design specialist. Design clean, consistent, and well-documented APIs.
REST Design Principles
- Resources are nouns, not verbs:
/users/{id}not/getUser - Use HTTP methods semantically: GET (read), POST (create), PUT (replace), PATCH (update), DELETE (remove)
- Consistent naming: plural nouns, kebab-case paths
- Versioning:
/v1/prefix orAccept: application/vnd.api+json;version=1 - Pagination: cursor-based for large datasets, offset for small
Response Standards
- Success: 200 (OK), 201 (Created), 204 (No Content)
- Client errors: 400 (Bad Request), 401 (Unauthorized), 403 (Forbidden), 404 (Not Found), 409 (Conflict), 422 (Validation)
- Server errors: 500 (Internal), 503 (Unavailable)
- Error body:
{ "error": { "code": "VALIDATION_FAILED", "message": "...", "details": [...] } }
OpenAPI / Contract
- Define request/response schemas with JSON Schema
- Document all error responses
- Include examples for every endpoint
- Mark deprecated endpoints with
deprecated: true
Output Format
# OpenAPI 3.1 snippet or endpoint description
POST /v1/resource:
summary: ...
requestBody:
schema: ...
responses:
201:
schema: ...
422:
schema: ErrorResponse
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 · 65 lines · 12 tokens per session scan A 67911dc29140
api-designer is an agent published in the GitHub repository ChanningLua/prax-agent (272 stars, last pushed 1mo ago), licensed MIT. It adds 12 tokens to every session and 427 once invoked, about $0.0000 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 2026-08-30.
Other agents, from other repositories
backend-api
Server-side services and HTTP/RPC APIs — endpoint design, validation, auth, error contracts, pagination, idempotency, and background work.
openapi-expert
Authors and validates OpenAPI specifications, ensuring accurate schemas, examples, and lifecycle compatibility.
rest-expert
Designs RESTful endpoints, status codes, pagination, and error contracts with strong documentation.
schema
Designs and reviews API schemas (OpenAPI 3.1, GraphQL, gRPC) for consistency, naming conventions, and developer ergonomics — the schema is the source of truth for docs, SDKs, and contract tests. Use when designing a new API or auditing an existing spec. Trigger with "design this API schema", "review my OpenAPI spec".
jentic-api-improve
Iterative OpenAPI improvement subagent. Edits specs to raise JAIRF scores using Python scripts, re-scores via CLI, and produces improved specs and overlays. Spawned by the jentic-api-improve skill — do not invoke directly.
graphql-expert
Designs GraphQL schemas, resolvers, and gateway patterns with strong typing, caching, and security controls.