android_current_app

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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It only states the action ('Get') without mentioning that this is a read-only operation, whether it requires special permissions, or how it behaves when no app is focused. For a tool that queries system state, this lack of behavioral context leaves an agent uncertain about side effects and prerequisites, earning a low score.

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 is a single, front-loaded sentence with no unnecessary words. It efficiently states the verb and resource without redundancy, making it highly concise and structurally sound.

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 simple getter with one optional parameter and no output schema, the description adequately explains what is returned (package name and activity). It does not elaborate on device selection or error handling, but given the tool's simplicity and the optional nature of the parameter, these omissions are minor. The description is complete enough for an agent to use the tool correctly in most scenarios.

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 has 100% description coverage for the single optional parameter deviceId ('Optional device ID'), and the tool description adds no additional meaning about this parameter. The description does not discuss how deviceId is used or its impact on results. With high schema coverage, the baseline is 3, and this description does not elevate it.

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 'Get' and names the exact resource: 'package name and activity of the currently focused foreground Android application.' This clearly distinguishes it from siblings like android_screenshot or android_ui_dump, which have different purposes. An agent can immediately understand what this tool does and how it differs.

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: use when you need the identity of the current foreground app. It does not explicitly list alternatives or when not to use it, but the specificity of the purpose makes the usage scenario obvious. Without exclusions or references to sibling tools, it falls short of a 5, but is above a 3 because the context is unambiguous.

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