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 skills/personamanagmentlayer/pcl/openapi-expertnpx skills add personamanagmentlayer/pcl --skill openapi-expertgit clone --depth 1 https://github.com/personamanagmentlayer/pclWrote 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/skills/personamanagmentlayer/pcl/openapi-expert)<a href="https://agentmods.dev/skills/personamanagmentlayer/pcl/openapi-expert"><img src="https://agentmods.dev/badge/skills/personamanagmentlayer/pcl/openapi-expert.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 5.1 | $0.00057 | $0.00985 |
| Opus 5 | $0.00028 | $0.00492 |
| Sonnet 5 | $0.00011 | $0.00197 |
| Haiku 4.5 | $0.00006 | $0.00098 |
Grade A, and why
openapi-expert 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 today.
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 — 185 lines — stays where its author put it; the contents beside it link to each section on GitHub.
OpenAPI Expert
Expert guidance for OpenAPI Specification (formerly Swagger) - industry-standard for describing RESTful APIs with automatic documentation and code generation.
Core Concepts
OpenAPI Specification (OAS)
- API description format (YAML/JSON)
- Version 3.1 (latest) and 3.0
- Machine-readable API contracts
- Automatic documentation generation
- Client/server code generation
- API validation and testing
Key Components
- Paths (endpoints)
- Operations (HTTP methods)
- Parameters
- Request/Response bodies
- Schemas (data models)
- Security schemes
- Components (reusable objects)
Advanced Features
Webhooks (OpenAPI 3.1)
webhooks:
postCreated:
post:
summary: Post created webhook
operationId: onPostCreated
requestBody:
content:
application/json:
schema:
$ref: '#/components/schemas/Post'
responses:
'200':
description: Webhook received
Polymorphism (oneOf/anyOf/allOf)
components:
schemas:
Pet:
oneOf:
- $ref: '#/components/schemas/Cat'
- $ref: '#/components/schemas/Dog'
discriminator:
propertyName: petType
mapping:
cat: '#/components/schemas/Cat'
dog: '#/components/schemas/Dog'
Cat:
allOf:
- $ref: '#/components/schemas/PetBase'
- type: object
properties:
petType:
type: string
enum: [cat]
meow:
type: string
Dog:
allOf:
- $ref: '#/components/schemas/PetBase'
- type: object
properties:
petType:
type: string
enum: [dog]
bark:
type: string
Code Generation
# Install OpenAPI Generator
npm install -g @openapitools/openapi-generator-cli
# Generate TypeScript client
openapi-generator-cli generate \
-i openapi.yaml \
-g typescript-axios \
-o ./client
# Generate Python Flask server
openapi-generator-cli generate \
-i openapi.yaml \
-g python-flask \
-o ./server
# Generate Java Spring server
openapi-generator-cli generate \
-i openapi.yaml \
-g spring \
-o ./server
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- today Changed · -321 lines · +36 tokens per session 4ac6f8609c2f
- 6d ago First seen · 506 lines · 21 tokens per session scan A 83b3a0c9015e
openapi-expert is a skill published in the GitHub repository personamanagmentlayer/pcl (41 stars, last pushed today), licensed Apache-2.0. It adds 57 tokens to every session and 985 once invoked, about $0.0003 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 2026-08-30.
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