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

Even though annotations are absent, the description adds meaningful behavioral context: it clearly explains that the 'held state' is not read from the device but is the last frame the server sent, a non-obvious behavior. It also distinguishes the attachment read from the state read. This is valuable transparency beyond the name and schema. It doesn't cover every detail (e.g., outcome if no controller attached), but overall it provides strong behavioral context.

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 with no filler. The primary purpose is front-loaded: 'Report whether...' and the first sentence covers the main function. The second sentence adds usage guidance and clarifies a behavioral nuance. 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?

The tool is simple (one parameter), the schema covers that parameter fully, and there is no output schema to worry about. The description tells the agent what it does, when to use it, and clarifies an important data-origin nuance. That is complete for an agent to correctly invoke and interpret the 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?

Schema coverage is 100% for the only parameter (udid), so the schema already documents it as 'Device serial number (UDID)'. The description doesn't add additional semantics for udid beyond what's in the schema. Baseline 3 is appropriate because the schema handles the parameter documentation.

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 clearly states the tool's purpose: 'Report whether a virtual game controller is currently attached...', 'what it is presenting as, and the last state that was sent to it.' It specifies the resource (virtual game controller on an Android device) and the verb (report). It also implies a distinction from sibling tools like device_gamepad_state and device_uhid_gamepad_state by focusing on status rather than setting state.

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 'Use to confirm device_gamepad_state took effect' explicitly states when to use this tool, and by implication that it should not be used for setting states. It also clarifies the source of data: 'The attachment is read from the device itself; the held state is the last frame this server sent.' This explains why it's appropriate for confirmation and not for live state.

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