You Might Not Need A Callback

What it does

Example prompts

• “/you-might-not-need-a-callback”

Workflow steps

7 steps, taken from the first numbered list in SKILL.md.

1. 1No observer tracks the reference: The function is only called inline in the same component, or passed to a non-memoized child, or used as…
2. 2useCallback with deps that change every render: If a dep is a plain object/array created inline, or state that changes on every…
3. 3useCallback on handlers passed only to native elements: — React never does reference equality on native element props. No benefit.
4. 4useCallback wrapping functions that return new objects/arrays: Stable function identity, unstable return value — memoization is at the…
5. 5useCallback with empty deps when deps are needed: Stale closure — reads initial values forever. This is a correctness bug, not just a…
6. 6Pairing useCallback + React.memo on trivially cheap renders: If the child renders in < 1ms and re-renders rarely, the memo infrastructure…
7. 7Internal helpers inside custom hooks wrapped for no observer: functions a hook only calls internally need no useCallback. Functions a hook…

What it can do on your machine

Read from SKILL.md and the folder at commit 546d4e7. 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

  Links to these hosts (documentation or services it may open):

  • react.dev

  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

You Might Not Need A Callback loads about 904 tokens when it runs. Until then it costs about 21 tokens; SKILL.md has 479 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~21

When it runs · the whole SKILL.md, loaded when a task matches

~904

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

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 simstudioai/sim at commit 546d4e7, republished under its Apache-2.0 licence (© simstudioai). 479 words, ~904 tokens.

name

you-might-not-need-a-callback

description

Analyze and fix useCallback anti-patterns in your code

argument-hint

[scope] [fix=true|false]

const idRef = useRef(id)
useEffect(() => { idRef.current = id }, [id])
const fetchData = useCallback(async () => {
  // use idRef.current instead of id
}, []) // empty deps because refs are used

© simstudioai, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/you-might-not-need-a-callback of simstudioai/sim.

Open the folder on GitHubat commit 546d4e7