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openapi

openapi is a skill for Claude Code from mrlm-xyz/demo-claude-marketplace. It costs 19 tokens per session (240 once invoked), scanned A, original, Apache-2.0.

Guidance for writing OpenAPI specifications, which are machine-readable descriptions of REST APIs. It covers endpoints, data shapes, examples, errors, security, and versioning.

In plain words
What is it for?
Use it to design or review API specifications, define request and response data, document authentication, and describe possible error responses.
Why use it?
It helps turn an API design into a precise shared contract that people and tools can understand. Clear schemas and documented errors also make invalid requests and breaking changes easier to catch.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the api-guardian plugin — 2 skills, 2 commands, 2 agents shipped together

not rated 35repo +1 2mo ago A scan SkillSpector: pass 19 tokens original Apache-2.0

Good fit Use it to design or review API specifications, define request and response data, document authentication, and describe possible error responses.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/mrlm-xyz/demo-claude-marketplace/openapi
View source ↗ mrlm-xyz/demo-claude-marketplace
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 mrlm-xyz/demo-claude-marketplace --skill openapi
Clone the repo
git clone --depth 1 https://github.com/mrlm-xyz/demo-claude-marketplace

Made for: Claude Code.

Or install api-guardian, the plugin that ships this one along with the rest of its 2 skills, 2 commands, 2 agents.

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 openapi

README.md
[![agentmods](https://agentmods.dev/badge/skills/mrlm-xyz/demo-claude-marketplace/openapi/github.svg)](https://agentmods.dev/skills/mrlm-xyz/demo-claude-marketplace/openapi)
Your own site
<a href="https://agentmods.dev/skills/mrlm-xyz/demo-claude-marketplace/openapi"><img src="https://agentmods.dev/badge/skills/mrlm-xyz/demo-claude-marketplace/openapi/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.

agentmods 80×15 button for openapi

Your own site · 80×15
<a href="https://agentmods.dev/skills/mrlm-xyz/demo-claude-marketplace/openapi"><img src="https://agentmods.dev/badge/skills/mrlm-xyz/demo-claude-marketplace/openapi.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 240 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00019 $0.00240
Opus 5.5 $0.00008 $0.00096
Sonnet 5.5 $0.00004 $0.00048
Haiku 4.5 $0.00002 $0.00024

Measured 2mo ago against content hash 20a530099cc1, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

openapi 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 2mo 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.

claude-plugins/api-guardian/skills/openapi/SKILL.md · 35 lines

What it actually says

OpenAPI Skill

You are an OpenAPI specification expert with deep knowledge of API design patterns and REST principles. Create clear, complete, and maintainable API specifications.

Core Principles

  • Specifications are contracts — be precise and complete
  • Schema validation prevents errors — define all types
  • Examples aid understanding — provide realistic samples
  • Consistency across endpoints — uniform patterns
  • Versioning prevents breaking changes
  • Security definitions are mandatory
  • Error responses need documentation
  • Descriptions should be clear and actionable

Best Practices

Define comprehensive schemas with appropriate types and constraints. Use references to avoid duplication. Include examples for all requests and responses. Document all possible status codes and error responses. Define security schemes and apply them consistently. Use tags for logical grouping. Provide clear descriptions for all endpoints, parameters, and schemas.

Files

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.

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. 2mo ago First seen · 35 lines · 19 tokens per session scan A 20a530099cc1

Subscribe to this mod's changes

openapi is a skill published in the GitHub repository mrlm-xyz/demo-claude-marketplace (35 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 19 tokens to every session and 240 once invoked, about $0.0001 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.

Backend and APIs
Related

openapi compared with skills from other repositories

openapi next to 6 skills from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
openapimrlm-xyz/demo-claude-marketplaceSkill352mo agoApache-2.0A19Claude Code
mem0-oss-to-platformmem0ai/mem0Skill69k3d agoApache-2.0A217Claude Code, Codex
azure-mgmt-botservice-dotnetmicrosoft/skillsSkill3.2ktodayMITA78Claude Code
fastapi-router-pymicrosoft/skillsSkill3.2ktodayMITA46Claude Code
api-designericrisco/rsc-harnessSkill5555d agoMITA105Claude Code, Codex
migrate-segw-to-raparc-mcp/arc-1Skill254todayMITA106Claude Code
telnyx-messaging-hosted-curlteam-telnyx/aiSkill225todayMITA45Claude Code