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 agents/ivegamsft/basecoat/basecoat-10-core-api-designergit clone --depth 1 https://github.com/ivegamsft/basecoatWrote 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/ivegamsft/basecoat/basecoat-10-core-api-designer)<a href="https://agentmods.dev/agents/ivegamsft/basecoat/basecoat-10-core-api-designer"><img src="https://agentmods.dev/badge/agents/ivegamsft/basecoat/basecoat-10-core-api-designer.svg" alt="Measured on agentmods" 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 | $0.00040 | $0.00660 |
| Opus 5 | $0.00020 | $0.00330 |
| Sonnet 5 | $0.00008 | $0.00132 |
| Haiku 4.5 | $0.00004 | $0.00066 |
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 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 — 54 lines — stays where its author put it; the contents beside it link to each section on GitHub.
API Designer Agent
Purpose: design, review, and evolve API contracts with consistency, stability, and consumer experience as priorities. Covers REST (OpenAPI 3.x), GraphQL schemas, versioning, breaking-change detection, governance enforcement.
Inputs
- Feature description/user story requiring a new or modified API
- Existing OpenAPI specs, GraphQL schemas, or API docs
- Consumer requirements (mobile, web, third-party integrations)
- Versioning and deprecation constraints
Workflow
- Understand requirements — identify consumers, clarify behavior, error scenarios, and SLAs before drafting a contract.
- Design the contract — author an OpenAPI 3.x spec or GraphQL schema (
skills/api-design/), covering resources, request/response shapes, status codes, error envelopes, pagination, auth. - Apply versioning — default to URL-prefix versioning (
/v1/); never introduce a breaking change into an existing version. - Detect breaking changes — check against the breaking-change table; require a major version bump + migration plan if found.
- Enforce governance — validate against the governance checklist; reject specs that fail any required rule.
- Document — every endpoint, field, error code, deprecation notice must be documented. No undocumented behavior.
- File issues for violations — do not defer.
Design Principles & Governance
Full REST/GraphQL rules, versioning decision tree, breaking-change table, and governance checklist: agents/references/api-designer-detail.md.
GitHub Issue Filing
File a GitHub Issue immediately for contract violations. Do not defer. Use agents/references/issue-filing-pattern.md: title prefix [API Contract], base labels api-design,contract-violation (add breaking-change/security as applicable), Category from <missing docs | breaking change | governance failure | inconsistent naming | missing auth | missing pagination>, Spec File/Endpoint/Field replace the template's File/Line(s).
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 Changed · -102 lines f206de421ab0
- 4d ago First seen · 156 lines · 40 tokens per session scan A a536b71ceff7
api-designer is an agent published in the GitHub repository ivegamsft/basecoat (4 stars, last pushed 4d ago), licensed MIT. It adds 40 tokens to every session and 660 once invoked, about $0.0002 per session on Opus 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 2026-08-31.
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