Launch an app

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the behavioral burden. It compensates well by explaining the default app selection logic (only non-system running app, else only installed app) and the SIM_APP_BUNDLE_ID override. It does not mention failure modes or behavior when multiple apps are running.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two focused sentences with no filler. Every clause adds information: target, context, default behavior, and override mechanism.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given a simple one-parameter tool with no output schema, this description covers invocation context, default selection, and override options. Minor gaps remain around error cases (multiple non-system apps, nothing to launch), but the core usage is complete enough.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema provides only a bare bundleId string, but the description clarifies its meaning, that it is optional, and how the default is determined. It stops short of giving an example or specifying bundle-id format.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a specific verb ('launch') and target ('app by bundle id on the booted simulator'), making the core action clear. It does not explicitly distinguish itself from the sibling open_app, so it stops short of a 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description conveys the intended context: launching an app on the booted simulator by bundle id, with automatic defaults. However, it gives no explicit guidance on when to prefer this over sibling tools like open_app or open_storybook.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.