Launch App

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

The annotation already declares destructiveHint: true, indicating the tool modifies device state. The description adds no further behavioral context (e.g., that the app becomes foreground, or that it may interrupt the current flow). With annotations covering the safety profile, the description is adequate but does not add extra value.

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?

The description consists of two short sentences, both front-loaded with the purpose. Every sentence earns its place: the first states the action, the second provides a practical tip. No unnecessary words.

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 the simplicity of the tool and the presence of annotations, the description is minimally adequate. However, it does not mention that the app must already be installed, what the expected result is (e.g., app becomes active), or any potential side effects beyond the destructive hint. A slightly more complete description would benefit the agent.

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 covers all three parameters with descriptions, but the description adds value by suggesting how to obtain the packageName (via list_apps_on_device), which aids parameter selection. This exceeds what the schema alone 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 clearly states the tool launches or opens an app on a mobile device, using the verb 'launch'. It distinguishes from sibling tools like mobile_install_app (installing) and mobile_terminate_app (closing) by focusing on opening an existing app.

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 provides clear context by instructing the agent to 'Use this to open a specific app' and includes a hint on how to find the package name via list_apps_on_device. However, it does not explicitly state when not to use this tool or mention alternative tools for related tasks.

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