get_phone_state

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

With no annotations, the description carries the burden of behavioral disclosure. It states what the tool returns (app, activity, keyboard state, focused element) and implies a lightweight read-only operation, but it doesn't explicitly mention permission requirements, side effects, or the structure of 'focused element.' Since the tool name and description strongly suggest a read-only getter, a neutral score is appropriate.

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 two sentences, tightly written, with the core purpose in the first sentence and a valuable use-case clarification in the second. Every word earns its place, and the structure front-loads the essential information.

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?

The tool is simple (one parameter) and has an output schema, so return values are covered. The description explains what the tool returns and when to use it, covering the core functional context. However, the parameter semantics are omitted, and the 'focused element' part could be ambiguous without further detail, holding it back from a perfect score.

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 one parameter 'device' with no description (coverage 0%), and the tool description does not mention the parameter at all. The agent is left to infer that 'device' refers to a device identifier from context, which is likely but not explicitly explained. The description adds no semantic value beyond the bare parameter name.

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 the specific verb 'Get' and clearly states the resource: 'current app, activity, keyboard state, and focused element.' It also distinguishes itself from sibling tools like get_elements and get_screen_tree by framing itself as a 'quick way to check what app/screen the device is on without parsing full elements.'

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 usage context: it's the go-to for a quick state check without parsing the full element hierarchy. It doesn't explicitly name sibling alternatives or state when not to use it, but the phrase 'quick way' and 'without parsing full elements' effectively communicates the intended scenario.

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