current_app

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

No annotations are supplied, so the description carries the burden alone. 'Return' implies a safe, side-effect-free read, and it discloses the scope of the answer, but it says nothing about edge cases such as no foreground app, a launcher/home screen, or whether a device must be connected.

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 front-loaded sentence with no filler, and it states the return scope immediately. Nothing could be removed without losing meaning.

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?

This is a simple zero-parameter read, but there is no output schema, so the description should say what the return looks like (a package name string, or a package/activity pair) rather than leaving 'package/activity' ambiguous. Adequate, but a real gap for an agent that must parse the result.

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 tool takes zero parameters, so there is no argument semantics to explain; the baseline of 4 applies. The description correctly refrains from inventing parameters.

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 gives a specific verb (Return) and a precise resource (the package/activity currently in the foreground), so an agent knows exactly what query is being answered. It does not explicitly distinguish itself from siblings like list_apps or open_app, which would have raised it to 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?

Usage is only implied: an agent can infer this is the way to check what is on screen right now, but the description never says when to prefer it over list_apps or get_ui_elements, nor states any prerequisite such as an active device connection.

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