launch_app

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

Annotations already declare readOnlyHint=false and openWorldHint=true, signaling a mutating, side-effectful operation. The description adds no further behavioral context—no side effects, failure modes, prerequisites, or return value. 'Launches an app' largely restates the tool name and the annotation's implication.

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?

A single 11-word sentence is information-dense and free of fluff. It is perfectly front-loaded with the action and target.

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?

The schema thoroughly documents all parameters and the annotations cover the safety profile, but the description omits expected output (e.g., simctl launch returns a PID), error cases (app not installed, simulator not booted), and any guidance on the env or terminate_running parameters. Adequate for a simple launch action but not complete.

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 input schema has 100% coverage with all four parameters described, so the baseline of 3 applies. The description's 'by bundle identifier' merely reinforces the required bundle_id parameter without adding semantics beyond what the schema already provides.

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 uses a specific verb ('Launches'), a clear resource ('an app on the iOS Simulator'), and an explicit method ('by bundle identifier'). This clearly distinguishes it from sibling tools like install_app, terminate_app, and open_url.

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 gives clear context: it launches an app on the iOS Simulator, so an agent knows when to reach for it. However, it does not explicitly mention alternatives or exclusions, such as needing to install the app first or ensuring the simulator is booted.

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