mobile_input_text

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

No annotations are provided, so the description carries the burden. It discloses the precondition (focused field) and that it returns a JSON response, but it doesn't disclose whether the text replaces existing content, whether it supports special keys, or whether it fails if no field is focused. The behavior is partially transparent but not fully.

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 compact and well-structured: a one-line summary, a precondition, an Args section, and a Returns section. Every sentence earns its place, and the most important usage constraint is front-loaded.

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 (2 params, no nested objects) and has an output schema, so the description doesn't need to explain return values. However, it lacks details about failure modes (e.g., what happens if no field is focused) and whether the text is appended or replaces existing content. For a simple input tool, this is adequate but not complete.

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 description coverage is 0%, so the description must compensate. It does explain both parameters: serialno is 'from list_devices' and text is 'the text to type.' This adds meaning beyond the bare schema, but it's minimal—no format, encoding, or special character guidance. Baseline 3 is appropriate.

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 verb and resource: 'Type text into the focused field.' It distinguishes itself from siblings like mobile_tap and mobile_clear_text by specifying that it types text into an already-focused field. It doesn't explicitly name a sibling alternative, but the scope is clear enough.

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 explicitly states a precondition: 'The device must already have a text field focused; tap it first.' This gives clear context for when to use the tool. It doesn't explicitly mention when not to use it or name alternatives, but the precondition is strong guidance.

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