You are an API mocking expert specializing in realistic mock services for development, testing, and demos. Design mocks that simulate real API behavior and enable parallel development.
28
21%
Does it follow best practices?
Impact
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No eval scenarios have been run
Passed
No known issues
Optimize this skill with Tessl
npx tessl skill review --optimize ./skills/api-testing-observability-api-mock/SKILL.mdQuality
Discovery
22%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This description reads more like a persona prompt ('You are an API mocking expert') than a skill description, using second person voice which violates the third-person requirement. It lacks concrete actions, explicit trigger guidance, and sufficient natural keywords to reliably distinguish it from other development or testing skills.
Suggestions
Rewrite in third person and list specific concrete actions, e.g., 'Generates mock API endpoints, creates realistic response fixtures, simulates error codes and latency, and builds stub services for integration testing.'
Add an explicit 'Use when...' clause with natural trigger terms, e.g., 'Use when the user asks to mock an API, create test stubs, fake API responses, set up a mock server, or simulate API behavior for development or testing.'
Remove the persona framing ('You are an API mocking expert') and replace with capability-focused language that helps Claude distinguish this skill from general testing or API development skills.
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | The description uses vague language like 'design mocks that simulate real API behavior' and 'enable parallel development' without listing concrete actions. It doesn't specify what actions are performed (e.g., generate mock endpoints, create response fixtures, simulate error codes). | 1 / 3 |
Completeness | The description partially addresses 'what' (design mocks) but in very vague terms, and completely lacks a 'Use when...' clause or any explicit trigger guidance for when Claude should select this skill. Per rubric guidelines, missing 'Use when' caps completeness at 2, and the weak 'what' brings it to 1. | 1 / 3 |
Trigger Term Quality | Contains some relevant keywords like 'API mocking', 'mock services', 'testing', and 'demos', but misses common user terms like 'stub', 'fake API', 'mock server', 'test doubles', 'API simulation', or specific tool names. | 2 / 3 |
Distinctiveness Conflict Risk | The term 'API mocking' provides some distinctiveness, but the broad mentions of 'development, testing, and demos' could overlap with general testing skills, API development skills, or demo-building skills. | 2 / 3 |
Total | 6 / 12 Passed |
Implementation
20%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This skill is a thin wrapper of generic instructions with no concrete, actionable content. It explains what API mocking is and when to use it—things Claude already knows—while deferring all actual implementation guidance to a bundle file that doesn't exist. The content lacks executable code examples, specific tool recommendations, or concrete workflows that would make it useful.
Suggestions
Add concrete, executable code examples showing how to set up a mock server (e.g., using Express, MSW, or WireMock) with at least one complete working example.
Remove or drastically shorten the 'Use this skill when', 'Do not use this skill when', 'Context', and 'Safety' sections—these explain concepts Claude already understands and waste token budget.
Include the referenced `resources/implementation-playbook.md` in the bundle, or inline the most critical templates and checklists directly in the skill body.
Add validation checkpoints to the workflow, such as verifying the mock matches the API contract schema before serving responses.
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The content is verbose and padded with sections that explain things Claude already knows (what API mocking is, when to use it, generic safety advice). The 'Context' section restates the description. 'Use this skill when' and 'Do not use this skill when' sections add little actionable value. Much of this is filler that doesn't teach Claude anything new. | 1 / 3 |
Actionability | There are no concrete code examples, no executable commands, no specific mock server setup instructions, and no copy-paste ready snippets. The instructions are abstract directives like 'Clarify the API contract' and 'Define mock routes' without showing how. The actual implementation is deferred to a referenced file that doesn't exist in the bundle. | 1 / 3 |
Workflow Clarity | The instructions section provides a rough sequence of steps (clarify contract → define routes → provide fixtures → document running), but there are no validation checkpoints, no feedback loops, and no explicit verification steps. The sequence is present but lacks the rigor needed for a multi-step workflow. | 2 / 3 |
Progressive Disclosure | The skill references `resources/implementation-playbook.md` for detailed implementation, which is a reasonable one-level-deep reference. However, the referenced file doesn't exist in the bundle, making the reference unverifiable. The main file itself contains too much boilerplate and not enough substantive overview content to serve as an effective entry point. | 2 / 3 |
Total | 6 / 12 Passed |
Validation
90%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 10 / 11 Passed
Validation for skill structure
| Criteria | Description | Result |
|---|---|---|
frontmatter_unknown_keys | Unknown frontmatter key(s) found; consider removing or moving to metadata | Warning |
Total | 10 / 11 Passed | |
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Table of Contents
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