API Discoverability for Agents

API Discoverability for Agents is a skill for Claude Code, Codex from niels-emmer/myace. It costs 51 tokens per session (919 once invoked), scanned A, original, MIT.

A practice for making self-hosted services describe their APIs in a machine-readable format, such as an OpenAPI file. It also tells agents to look for that description before probing an unfamiliar service.

In plain words
What is it for?
Use it when building a service or integrating with one to add, find, and update API descriptions before inspecting the user interface or testing endpoints manually.
Why use it?
It reduces trial-and-error integration by giving developers and coding agents a reliable map of available endpoints.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for aider. Also seen: mentions Codex; built for aider; mentions OpenCode.

Good fit Use it when building a service or integrating with one to add, find, and update API descriptions before inspecting the user interface or testing endpoints manually.

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Install with agentmods
npx agentmods add skills/niels-emmer/myace/api-discoverability
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.

Any agent
npx skills add niels-emmer/myace --skill api-discoverability
Clone the repo
git clone --depth 1 https://github.com/niels-emmer/myace

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for API Discoverability for Agents

README.md
[![agentmods](https://agentmods.dev/badge/skills/niels-emmer/myace/api-discoverability.svg)](https://agentmods.dev/skills/niels-emmer/myace/api-discoverability)
Your own site
<a href="https://agentmods.dev/skills/niels-emmer/myace/api-discoverability"><img src="https://agentmods.dev/badge/skills/niels-emmer/myace/api-discoverability.svg" alt="Measured on agentmods" height="20"></a>
Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 919 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00051 $0.00919
Opus 5 $0.00026 $0.00460
Sonnet 5 $0.00010 $0.00184
Haiku 4.5 $0.00005 $0.00092

Measured 4d ago against content hash 1f15b342012e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

API Discoverability for Agents scanned grade A with 1 finding 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 4d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

3. If supported, add the generator and serve the spec at a conventional path (`/openapi.json` preferred; `/swagger.json`, `/api-docs` acceptable). Verify with `curl`.
collections/additional/backend/skills/api-discoverability/SKILL.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Purpose

Agents integrate with services by reading a machine-readable API description instead of crawling a web UI or reverse-engineering endpoints by trial and error. This skill makes that the default: bake the description in when you build a service, and look for it before you probe when you integrate with one. It's the discoverability half of the API story — api-design-checklist keeps an API internally consistent; this skill makes sure agents can actually find and use it.

When to use it

  • BUILDING a new self-hosted service — after scaffolding, before considering it done.
  • INTEGRATING with an existing unfamiliar service — before crawling the UI or probing endpoints by trial and error.

Decision tree

New service → bake-in. Existing service → discover-first, then probe-and-write-back only if no description exists.

Bake-in (new services)

Treat the API description as a required step before "done", not optional polish.

  1. Detect the framework from the project manifest (package.json, pyproject.toml, go.mod, ...).
  2. Check for cheap OpenAPI support — FastAPI and ASP.NET Core serve /openapi.json with zero extra code.
  3. If supported, add the generator and serve the spec at a conventional path (/openapi.json preferred; /swagger.json, /api-docs acceptable). Verify with curl.
  4. Otherwise write a minimal API.md at the repo root covering every endpoint: method, path, params, and a working curl example.
  5. Verify before done: every route appears in the spec or API.md, the curl examples actually work, and the spec path is reachable at the conventional location.

Discover-first (existing services)

  1. Probe conventional spec paths: /openapi.json, /swagger.json, /api-docs, /swagger-ui/, /redoc, /api, /docs.
  2. Search the repo: API.md, a README API section, docs/, OpenAPI yaml files, Postman collections, *.http files.
  3. Use what you find — extract base URL, auth scheme, endpoints, params, request/response shapes. Integrate against it; do not re-derive by probing.
  4. Only if neither a spec path nor repo documentation exists, fall back to probe-and-write-back.

Read the full file on GitHub · 59 lines

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. 4d ago First seen · 59 lines · 51 tokens per session scan A 1f15b342012e

Subscribe to this mod's changes

API Discoverability for Agents is a skill published in the GitHub repository niels-emmer/myace (1 stars, last pushed yesterday), licensed MIT. It adds 51 tokens to every session and 919 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.