Agent skill

Testing API Assertions

Verify API requests in tests. An agent skill from stacklok/toolhive-studio.

Apache-2.0Auto-check passedAgent Workflows

Install Testing API Assertions

skills CLI

$ npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install stacklok/toolhive-studio testing-api-assertions --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/stacklok/toolhive-studio.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.codex/skills/testing-api-assertions .claude/skills/testing-api-assertions && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "testing-api-assertions" agent skill from https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions into .claude/skills/testing-api-assertions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing-api-assertions", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install stacklok/toolhive-studio testing-api-assertions --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/stacklok/toolhive-studio.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.codex/skills/testing-api-assertions .agents/skills/testing-api-assertions && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "testing-api-assertions" agent skill from https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions into .agents/skills/testing-api-assertions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing-api-assertions", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install stacklok/toolhive-studio testing-api-assertions --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/stacklok/toolhive-studio.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.codex/skills/testing-api-assertions .cursor/skills/testing-api-assertions && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "testing-api-assertions" agent skill from https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions into .cursor/skills/testing-api-assertions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing-api-assertions", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/stacklok/toolhive-studio.git --path .codex/skills/testing-api-assertions

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install stacklok/toolhive-studio testing-api-assertions --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/stacklok/toolhive-studio.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.codex/skills/testing-api-assertions .gemini/skills/testing-api-assertions && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "testing-api-assertions" agent skill from https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions into .gemini/skills/testing-api-assertions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing-api-assertions", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install stacklok/toolhive-studio testing-api-assertions

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/stacklok/toolhive-studio.git skills-src && mkdir -p .github/skills && cp -r skills-src/.codex/skills/testing-api-assertions .github/skills/testing-api-assertions && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "testing-api-assertions" agent skill from https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions into .github/skills/testing-api-assertions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing-api-assertions", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install stacklok/toolhive-studio testing-api-assertions --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/stacklok/toolhive-studio.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.codex/skills/testing-api-assertions .opencode/skills/testing-api-assertions && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "testing-api-assertions" agent skill from https://github.com/stacklok/toolhive-studio/tree/main/.codex/skills/testing-api-assertions into .opencode/skills/testing-api-assertions/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing-api-assertions", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: testing-api-assertions
GitHub stars: 170
Token cost: ~993 tokens
SKILL.md length: 218 words
Files: 1
Skills in repo: 9
Repo updated: Oct 7, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Verify API requests in tests. An agent skill from stacklok/toolhive-studio.

Testing that correct API calls are made for create
SKILL.md covers When to Use Request Assertions, recordRequests(), Recorded Request Shape and Common Patterns, plus 3 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
Delete operations

What it does

Testing API Assertions is an agent skill from stacklok/toolhive-studio. Verify API requests in tests. Use when testing that correct API calls are made for create, update, or delete operations. Use when testing mutations, form submissions, or actions with backend side effects.

Its SKILL.md is about 990 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Agent Workflows, covering MCP servers. It works with Model Context Protocol. The repository describes itself as: ToolHive is an application that allows you to install, manage and run MCP servers and connect them to AI agents. The licence is Apache-2.0.

When your agent uses it

Testing that correct API calls are made for create
Delete operations
Testing mutations
Form submissions

Example prompts

“/testing-api-assertions”

What it can do on your machine

Read from SKILL.md and the folder at commit 87f7a55. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Testing API Assertions loads about 993 tokens when it runs. Until then it costs about 57 tokens; SKILL.md has 218 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~57
When it runs · the whole SKILL.md, loaded when a task matches: ~993

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from stacklok/toolhive-studio at commit 87f7a55, republished under its Apache-2.0 licence (© stacklok). 218 words, ~993 tokens.

Download SKILL.mdSave it as .claude/skills/testing-api-assertions/SKILL.md (or your agent's skills folder).

name: testing-api-assertions
description: Verify API requests in tests. Use when testing that correct API calls are made for create, update, or delete operations. Use when testing mutations, form submissions, or actions with backend side effects.

Testing API Assertions

Verify that your code sends the correct API requests for operations with side effects.

When to Use Request Assertions

DO use for operations with side effects:

Creating resources (POST)
Updating resources (PUT/PATCH)
Deleting resources (DELETE)
Any mutation that changes backend state

DON'T use for read operations:

Fetching data (GET)
For these, just verify the component displays the data correctly
The mock API is not stateful, so verifying GET requests adds no value

recordRequests()

Use recordRequests() to capture all API requests made during a test:

typescript

import { recordRequests } from '@/common/mocks/node'

it('creates a group with correct payload', async () => {
  const rec = recordRequests()

  // ... perform action that triggers API call ...
  await userEvent.click(screen.getByRole('button', { name: /create/i }))

  // Find the request
  const request = rec.recordedRequests.find(
    (r) => r.method === 'POST' && r.pathname === '/api/v1beta/groups'
  )

  // Assert it was made with correct data
  expect(request).toBeDefined()
  expect(request?.payload).toEqual({ name: 'my-group' })
})

Recorded Request Shape

Each recorded request contains:

typescript

{
  pathname: '/api/v1beta/groups',      // URL path
  method: 'POST',                       // HTTP method
  payload: { name: 'my-group' },        // Parsed JSON body (if present)
  search: { filter: 'active' },         // Query parameters
}

Common Patterns

Verify POST payload

typescript

const rec = recordRequests()

// ... trigger create action ...

const createRequest = rec.recordedRequests.find(
  (r) => r.method === 'POST' && r.pathname === '/api/v1beta/workloads'
)
expect(createRequest?.payload).toMatchObject({
  name: 'my-server',
  group: 'default',
})

Verify DELETE was called

typescript

const rec = recordRequests()

// ... trigger delete action ...

const deleteRequest = rec.recordedRequests.find(
  (r) =>
    r.method === 'DELETE' && r.pathname === '/api/v1beta/workloads/my-server'
)
expect(deleteRequest).toBeDefined()

Verify request order

typescript

const rec = recordRequests()

// ... trigger actions ...

const postRequests = rec.recordedRequests.filter((r) => r.method === 'POST')
const groupIndex = postRequests.findIndex((r) => r.pathname.includes('/groups'))
const workloadIndex = postRequests.findIndex((r) =>
  r.pathname.includes('/workloads')
)

// Group must be created before workload
expect(groupIndex).toBeLessThan(workloadIndex)

Verify request count

typescript

const rec = recordRequests()

// ... trigger batch action ...

const deleteRequests = rec.recordedRequests.filter(
  (r) =>
    r.method === 'DELETE' && r.pathname.startsWith('/api/v1beta/workloads/')
)
expect(deleteRequests).toHaveLength(3)

Important Notes

recordRequests() clears previous recordings when called
Call it at the start of your test, before triggering actions
Each test starts fresh - recordings don't persist between tests
Use toMatchObject() for partial matching when payload has extra fields

When NOT to Use This

For read operations (GET) where you need to verify query parameters are sent correctly, don't use recordRequests(). Instead, use conditional overrides that return different data based on params, then verify the UI shows the expected data. See testing-api-overrides skill.

This approach is more robust because it tests actual user-facing behavior.

testing-with-api-mocks - Auto-generated mocks and fixture basics
testing-api-overrides - Conditional responses for testing filters/params (read operations)

Files

Just SKILL.md in .codex/skills/testing-api-assertions of stacklok/toolhive-studio.

Open the folder on GitHubat commit 87f7a55

Compare with similar skills

Testing API Assertions next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Testing API Assertions compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Testing API Assertions this skillstacklok/toolhive-studio	170	—	~993	Automated safety check: Pass	Apache-2.0	today
MCP Server Builderanthropics/skills	180k	62 repos	~2.3k	Automated safety check: Pass	Apache-2.0	2 days ago
MCP Server BuildershareAI-lab/learn-claude-code	78k	5 repos	~1.2k	Automated safety check: Pass	MIT	9 days ago
MCP Integration for Pluginsanthropics/claude-plugins-official	37k	11 repos	~3.1k	Automated safety check: Pass	Apache-2.0	today
Fastmcp Client CLIPrefectHQ/fastmcp	28k	1 repos	~823	Automated safety check: Pass	Apache-2.0	today
Crush Configurationcharmbracelet/crush	29k	—	~3.7k	Automated safety check: Pass	Custom licence	today

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Questions about Testing API Assertions

What does Testing API Assertions do?

Verify API requests in tests. An agent skill from stacklok/toolhive-studio. Testing API Assertions is an agent skill from stacklok/toolhive-studio. Verify API requests in tests.

When should I use Testing API Assertions?

Testing API Assertions fits situations like: testing that correct API calls are made for create; delete operations; testing mutations; form submissions.

How do I install Testing API Assertions in Claude Code?

Run `npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a claude-code`. Or copy the skill folder (.codex/skills/testing-api-assertions in stacklok/toolhive-studio) into .claude/skills/testing-api-assertions in your project. Claude Code loads it when a task matches its description.

How do I install Testing API Assertions in Codex?

Run `npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a codex`. Or copy the skill folder (.codex/skills/testing-api-assertions in stacklok/toolhive-studio) into .agents/skills/testing-api-assertions in your project. Codex loads it when a task matches its description.

Can I use Testing API Assertions in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add stacklok/toolhive-studio --skill testing-api-assertions -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/testing-api-assertions, .gemini/skills/testing-api-assertions, .github/skills/testing-api-assertions and .opencode/skills/testing-api-assertions in your project.

What does Testing API Assertions need to run?

SKILL.md names no scripts, command-line tools or credentials: Testing API Assertions is instructions for the agent only.

Does Testing API Assertions access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Testing API Assertions safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Testing API Assertions use?

Testing API Assertions is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Testing API Assertions use?

About 993 tokens (SKILL.md is roughly 4k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Testing API Assertions?

Skills that share tags, products or a category with Testing API Assertions: MCP Server Builder (anthropics/skills, 180k stars), MCP Server Builder (shareAI-lab/learn-claude-code, 78k stars), MCP Integration for Plugins (anthropics/claude-plugins-official, 37k stars) and Fastmcp Client CLI (PrefectHQ/fastmcp, 28k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Testing API Assertions?

stacklok (a GitHub organization) maintains it in stacklok/toolhive-studio, which has 170 GitHub stars. The repository holds 9 skills in this directory. The repository was last updated on October 7, 2026.

Source: stacklok/toolhive-studio on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Testing API Assertions

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Testing API Assertions

When to Use Request Assertions

recordRequests()

Recorded Request Shape

Common Patterns

Verify POST payload

Verify DELETE was called

Verify request order

Verify request count

Important Notes

When NOT to Use This

Related Skills

Files

Compare with similar skills

Similar skills

More from stacklok/toolhive-studio

Related

Questions about Testing API Assertions