mobile_current_app

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

With no annotations, the description carries the behavioral burden; the read-only nature is conveyed by 'Get' and the response shape is stated as a JSON envelope with app_name and package_name. It does not explicitly say there are no side effects, but for a read-only getter this is adequate.

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?

Three short, labeled sections—purpose, args, returns—with no filler. The key action is front-loaded and every sentence earns its place.

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?

For a one-parameter getter with an output schema, the description covers purpose, parameter source, and return contents. Minor gap: it could explicitly name the sibling tools it is not, and could confirm no state change.

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?

Since schema coverage is 0%, the description compensates by explaining serialno as 'The mobile device serialno, from list_devices,' which is more actionable than the schema's bare title. It does not give an example string, but the source tool is sufficient.

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 opening sentence, 'Get the app currently in the foreground,' uses a specific verb and resource and clearly distinguishes this from sibling tools like mobile_stop_current_app and mobile_launch_app. It does not restate the tool name without adding meaning.

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?

It gives a clear, immediate use case and the key prerequisite: serialno must come from list_devices. It does not explicitly point to alternatives or tell the agent when not to use it, so it misses the top tier.

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