api-testing

api-testing is a skill for Claude Code from cyanheads/workflows-mcp-server. It costs 46 tokens per session (8,153 once invoked), scanned A, a copy of api-testing, Apache-2.0.

A testing guide for MCP tool and resource handlers using Vitest, a JavaScript testing framework. It describes mock request contexts, HTTP fakes, contract checks, error assertions, and test organization.

In plain words
What is it for?
Use it to write isolated handler tests, simulate sessions and upstream requests, verify formatted results and errors, and create in-memory storage for tests.
Why use it?
It removes guesswork when testing handlers without running the entire server. It helps tests check observable behavior instead of depending on internal code structure.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the workflows-mcp-server plugin — 33 skills, 1 MCP server shipped together

Good fit Use it to write isolated handler tests, simulate sessions and upstream requests, verify formatted results and errors, and create in-memory storage for tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/cyanheads/workflows-mcp-server/api-testing
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 cyanheads/workflows-mcp-server --skill api-testing
Clone the repo
git clone --depth 1 https://github.com/cyanheads/workflows-mcp-server

Made for: Claude Code.

Or install workflows-mcp-server, the plugin that ships this one along with the rest of its 33 skills, 1 MCP server.

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-testing

README.md
[![agentmods](https://agentmods.dev/badge/skills/cyanheads/workflows-mcp-server/api-testing/github.svg)](https://agentmods.dev/skills/cyanheads/workflows-mcp-server/api-testing)
Your own site
<a href="https://agentmods.dev/skills/cyanheads/workflows-mcp-server/api-testing"><img src="https://agentmods.dev/badge/skills/cyanheads/workflows-mcp-server/api-testing/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-testing

Your own site · 80×15
<a href="https://agentmods.dev/skills/cyanheads/workflows-mcp-server/api-testing"><img src="https://agentmods.dev/badge/skills/cyanheads/workflows-mcp-server/api-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 8,153 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.
Origin 100% copy Near-identical to another mod 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 $0.00046 $0.08153
Opus 5.5 $0.00018 $0.03261
Sonnet 5.5 $0.00009 $0.01631
Haiku 4.5 $0.00005 $0.00815

Measured yesterday against content hash 82091983a274, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

api-testing 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 yesterday.

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.

Origin

This is a copy

100% identical to api-testing — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

framework-skills/api-testing/SKILL.md · 578 lines

How it starts

The opening of the file, as written. The whole thing — 578 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Overview

Tests target handler behavior directly — call handler(input, ctx), assert on the return value or thrown error. The framework's handler factory (try/catch, formatting, telemetry) is not involved. Use createMockContext from @cyanheads/mcp-ts-core/testing to construct the ctx argument.

Additional exports from /testing: createMockSession() binds a mock handler context to an HTTP session; createFetchMock() provides a strict upstream HTTP fake; runToolContract() executes a definition through schema, handler, formatting, enrichment/content, and production-shaped error-envelope checks. createMockLogger() returns a standalone MockContextLogger, createInMemoryStorage(options?) provides a real StorageService backed by InMemoryProvider, and expectInputRequired(run) returns the input_required result a multi-round-trip handler asked for (see Mock inputs).

Other testing subpaths: /testing/vitest (fixtures and conformance suites, below), /testing/fuzz (see Fuzz testing), and /testing/apps, whose renderAppTool renders an app tool's ui:// view against your server (a stdio command or an HTTP URL) in a headless MCP Apps host and reports initialization, errors, CSP violations, the view↔host messages, and screenshots. It needs the optional peers @modelcontextprotocol/client and @modelcontextprotocol/ext-apps plus a chrome-headless-shell build; the field-test skill covers installing one and reading the report.

Philosophy: Test behavior, not implementation. Refactors should not break tests. Match the repo's existing test layout: fresh scaffolds use tests/, while colocated src/**/*.test.ts files are also supported. Integration tests at I/O boundaries over unit tests of internals.


mcpTest — fixture-based Vitest test

mcpTest is a test.extend-based Vitest test that provides ctx, session, fetchMock, and storage as per-test fixtures — fresh instances for every test, eliminating boilerplate and enforcing isolation automatically. fetchMock is installed as globalThis.fetch only when requested by a test and restored afterward.

Read the full file on GitHub · 578 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. yesterday Changed · +2 lines 82091983a274
  2. 19d ago Changed · +46 lines 950eca924646
  3. 1mo ago Changed · +2 lines a1c8e82396ba
  4. 1mo ago First seen · 528 lines · 46 tokens per session scan A 1958f0095306

Subscribe to this mod's changes

api-testing is a skill published in the GitHub repository cyanheads/workflows-mcp-server (31 stars, last pushed yesterday), licensed Apache-2.0. It adds 46 tokens to every session and 8,153 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 100% identical to api-testing, differing in 0 lines, and is treated as a copy.

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