Type Text

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

Annotations already indicate readOnlyHint=false and destructiveHint=false, so the description is not required to restate those. It adds the useful context that input targets the focused element, but it does not disclose whether text appends to or replaces existing content, whether special keys are supported, or what happens after submission. These are moderate gaps but not contradictions.

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 that communicates the essential action and target without any filler. Every word earns its place, and it is appropriately sized for a simple input tool.

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 tool with fully documented parameters and no output schema, the description is mostly complete: it states the action and the target element. It could be slightly richer by noting that the element must already be focused, but that is already implied by the phrase 'focused element'.

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 100%, with all three parameters (text, device, submit) clearly described in the input schema. The description adds no additional parameter-level detail, so the baseline score of 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 uses a specific verb ('Type') and a clear resource ('the focused element'), making the tool's function immediately obvious. It is easily distinguished from sibling tools like mobile_click_on_screen_at_coordinates or mobile_press_button because it specifically handles text input.

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 implies the tool should be used when text needs to be entered into an already-focused element, but it does not explicitly state when to use it versus alternatives or mention any prerequisites beyond focus. There is no exclusion guidance or comparison to other input-related siblings.

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