api-mock-helper

api-mock-helper is a skill for Claude Code, Codex from LambdaTest/agent-skills. It costs 145 tokens per session (1,483 once invoked), scanned A, original, MIT.

A coding assistant skill for creating simulated API servers, endpoint stubs, test data, and isolated test environments. An API is a defined way for software to exchange requests and responses.

In plain words
What is it for?
Use it to prepare WireMock, Prism, MSW, Pact, Postman, VCR, or in-memory mocks for local development, frontend work, unit tests, contract tests, and record-and-replay testing.
Why use it?
It lets developers build against predictable fake responses when a real service is unavailable, incomplete, or unsafe to use during testing.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to prepare WireMock, Prism, MSW, Pact, Postman, VCR, or in-memory mocks for local development, frontend work, unit tests, contract tests, and record-and-replay testing.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/lambdatest/agent-skills/api-mocking
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 LambdaTest/agent-skills --skill api-mocking
Clone the repo
git clone --depth 1 https://github.com/LambdaTest/agent-skills

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-mock-helper

README.md
[![agentmods](https://agentmods.dev/badge/skills/lambdatest/agent-skills/api-mocking/github.svg)](https://agentmods.dev/skills/lambdatest/agent-skills/api-mocking)
Your own site
<a href="https://agentmods.dev/skills/lambdatest/agent-skills/api-mocking"><img src="https://agentmods.dev/badge/skills/lambdatest/agent-skills/api-mocking/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 api-mock-helper

Your own site · 80×15
<a href="https://agentmods.dev/skills/lambdatest/agent-skills/api-mocking"><img src="https://agentmods.dev/badge/skills/lambdatest/agent-skills/api-mocking.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 145 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,483 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium Data Exfiltration · line 175
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
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 $0.00145 $0.01483
Opus 5.5 $0.00058 $0.00593
Sonnet 5.5 $0.00029 $0.00297
Haiku 4.5 $0.00015 $0.00148

Measured 1mo ago against content hash de2a9fb8e95e, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

api-mock-helper 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 1mo 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.

api-skill/api-mocking/SKILL.md · 201 lines

How it starts

The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.

API Mock & Sandbox Skill

Generate mock servers, stubs, fixtures, and sandbox environments for any API.


Mock Strategy Selection

Scenario Tool / Approach
Frontend dev against unbuilt backend WireMock / Prism / MSW
Unit tests (in-process) In-memory mock functions
Contract testing Pact (consumer-driven contracts)
Postman testing Postman Mock Server
Local development Prism CLI from OpenAPI spec
Record & replay real API VCR (Python/Ruby), nock recordings

WireMock Stub Definition

{
  "request": {
    "method": "GET",
    "urlPathPattern": "/api/v1/users/([a-z0-9-]+)"
  },
  "response": {
    "status": 200,
    "headers": { "Content-Type": "application/json" },
    "jsonBody": {
      "id": "{{request.pathSegments.[3]}}",
      "name": "Alice Smith",
      "email": "[email protected]",
      "created_at": "2024-01-01T00:00:00Z"
    }
  }
}

WireMock Stateful Scenario

[
  {
    "scenarioName": "Order flow",
    "requiredScenarioState": "Started",
    "newScenarioState": "Paid",
    "request": { "method": "POST", "url": "/api/v1/orders" },
    "response": { "status": 201, "jsonBody": { "id": "ord_123", "status": "pending" } }
  },
  {
    "scenarioName": "Order flow",
    "requiredScenarioState": "Paid",
    "request": { "method": "GET", "url": "/api/v1/orders/ord_123" },
    "response": { "status": 200, "jsonBody": { "id": "ord_123", "status": "paid" } }
  }
]

Mock Service Worker (MSW — browser/Node.js)

import { http, HttpResponse } from 'msw';

export const handlers = [
  http.get('/api/v1/users', () => {
    return HttpResponse.json({
      data: [
        { id: 'usr_1', name: 'Alice', email: '[email protected]' },
        { id: 'usr_2', name: 'Bob', email: '[email protected]' },
      ],
      pagination: { total: 2, page: 1, limit: 20 }
    });
  }),

  http.post('/api/v1/users', async ({ request }) => {
    const body = await request.json();
    return HttpResponse.json(
      { id: 'usr_new', ...body, created_at: new Date().toISOString() },
      { status: 201 }
    );
  }),

  http.get('/api/v1/users/:id', ({ params }) => {
    if (params.id === 'not-found') {
      return HttpResponse.json({ error: 'NOT_FOUND' }, { status: 404 });
    }
    return HttpResponse.json({ id: params.id, name: 'Alice' });
  }),
];

Read the full file on GitHub · 201 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. 1mo ago First seen · 201 lines · 145 tokens per session scan A de2a9fb8e95e

Subscribe to this mod's changes

api-mock-helper is a skill published in the GitHub repository LambdaTest/agent-skills (376 stars, last pushed 6d ago), licensed MIT. It adds 145 tokens to every session and 1,483 once invoked, about $0.0006 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.

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