Lean and efficient throughout: it assumes Claude's competence (no "what is asyncio" preamble) and jumps to install/mode/scoping/fixtures with executable snippets, where the only explanatory prose states non-obvious gotchas like "coroutine tests are collected but never awaited".

Every section gives fully executable, copy-paste-ready guidance: pip installs, pyproject.toml blocks, pytestmark usage, loop_scope decorators, AsyncMock with assert_awaited_once_with, and an httpx AsyncClient + ASGITransport example.

A clearly sequenced 7-step process (Install -> mode -> mark -> scope -> fixtures -> mock -> framework clients) with an explicit verification checkpoint in Step 1 ("pytest --co -q") and an anti-patterns/Limitations section for error recovery.

The spine is an overview with well-signaled one-level-deep references to real files (references/asyncmock-assertions.md and references/framework-clients.md) that contain exactly the promised content with no nested references, plus a curated external-docs References section.

Lists multiple concrete actions ("installs the plugin", "selects asyncio_mode (auto vs strict)", "scopes event loops (function/class/module/session)", "writes async fixtures with @pytest_asyncio.fixture", "mocks coroutines with AsyncMock", "tests FastAPI ... and aiohttp"), matching the score-3 anchor.

Explicitly answers both what (the enumerated action list) and when ("Use when a Python project contains async def test_ functions, FastAPI/aiohttp endpoints, or any asyncio-based code"), plus an explicit "Do NOT use" exclusion clause.

Uses natural terms a user would say ("async Python tests", "pytest-asyncio", "FastAPI/aiohttp endpoints", "asyncio-based code", "async def test_ functions") with good coverage of the niche's common phrasings.

A clear asyncio-specific niche with distinct triggers and an explicit conflict-avoidance clause naming pytest-tests as the alternative for non-async pytest patterns, making wrong-skill triggering unlikely.