How to use the No Bare Casts agent skill (no-bare-casts)

What is an agent skill, and what does this one make the agent do?

An agent skill is a folder with a SKILL.md file that an AI agent reads when a request matches the skill's description. This one, named no-bare-casts, applies when the agent writes or edits TypeScript or TSX production code, modifies a file that already contains a bare 'as' cast, meets 'as unknown as', or reviews a cast site.

When it applies, the agent works through a six-step decision tree in order before keeping a cast: tighten the input type, add a runtime check such as a type predicate, restructure a generic, use 'satisfies', use castAs<T>(value) when the value already satisfies T, and only as a last resort use blindCast<T, "Reason">(value) with a specific written reason. Test files (*.test.ts, *.test-d.ts, test/**/*.ts) are exempt.

• Blind casts require a Reason literal that a reviewer can evaluate; vague reasons like 'trust me' are rejected by the skill's guidance.
• When touching a file with a bare 'as' cast, the agent should convert it to an accepted form or remove it.

Install the skill from the ZIP

Download the ZIP for the skill from this page and unzip it. The skill is a folder containing SKILL.md. Place that folder in one of two locations: ~/.claude/skills/ to make it available across your projects, or a project's .claude/skills/ folder to share it with one repository.

Alternatively, in the Claude apps, open Settings, go to Capabilities, and upload the skill under Skills.

• Personal install: ~/.claude/skills/no-bare-casts/
• Project install: .claude/skills/no-bare-casts/ inside your repository

Trigger the skill with natural requests

You do not need a special command. The agent loads the skill when your request touches the situations in its description. Plain requests work well, for example asking the agent to fix a type error without a cast, or to review a file for 'as' casts.

Name the situation in your request so the match is obvious, especially when working on a file that already has casts.

• "This type error is fixed with an as cast. Can you find a way to type it properly instead?"
• "Review src/ for bare as casts and convert them using the no-bare-casts rules."
• "I'm editing this file that has an as unknown as. What should it become?"

What the skill needs from your project

The skill assumes a TypeScript codebase. Its helper forms import from '@internal/utils/casts', which provides blindCast and castAs. Without that module the helper suggestions point at imports that do not exist, so the skill is a poor fit for projects outside Prisma's internal layout unless you adapt those paths yourself.

The cast-count check refers to the pnpm lint:ratchets CI script. The skill also says this CI ratchet rejects per-PR increases in cast count.

• TypeScript codebase
• '@internal/utils/casts' module exposing blindCast and castAs for the helper forms
• pnpm lint:ratchets script for the cast-count check referenced in the skill

Safety notes: scripts and network

According to the item's listing, this skill runs no scripts and uses no network. It consists of a single file, SKILL.md, containing instructions for the agent. Review the file yourself before installing any skill, since it changes how the agent writes code.

• Runs scripts: no
• Uses network: no
• Files: SKILL.md only

Tips for getting good results

Expect the agent to try type tightening and runtime predicates before reaching for a helper. If it proposes blindCast, check that the Reason names a concrete constraint. A weak reason is a sign the type design needs another look.

Use the skill on refactors of cast-heavy files, because the convert-when-you-touch rule means each edit reduces the total over time.

• Give the agent the file and the type error together so it can work through the decision tree.
• For throwaway prototypes, consider turning the skill off, since it may slow work that does not need strict types.