app.current

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

No annotations are provided, so the description carries the full behavioral burden, and it discloses almost nothing: it does not confirm this is a read-only query, nor does it describe what happens if no app is in the foreground or whether the call is cheap/fast. Only the implicit read semantics of 'current' hint at the safety profile.

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 five-character phrase with zero waste and the key qualifier ('current') front-loaded. It is terse rather than bloated, though it borders on under-specification for a tool whose entire purpose is its return value.

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?

With no output schema and no parameters, the description is the only place the return value could be documented, and it does not say whether the result is a package name, an activity name, a display label, or null when nothing is focused. That omission matters for a query-only tool.

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 per the rubric the baseline is 4. There is nothing for the description to disambiguate on the input side.

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 phrase '当前前台应用' (current foreground app) names a specific resource and, by implication, a query verb, and it is clearly distinct from siblings like app.list, app.launch, and app.stop. It is a noun phrase rather than an explicit verb, but an agent can tell what it retrieves without opening anything else.

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?

There is no when-to-use guidance, no mention of alternatives (e.g. app.list for all apps), and no stated preconditions. The agent must infer from the name alone that this is the tool for checking which app is currently on screen.

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