Clear the focused text field on Android by removing its characters: reads the current text length from the UI and sends exactly that many DELETE (backspace) keycodes, after moving the cursor to the end. Tap the field to focus it first. To clear and re-type in one call, use device_type with clearFirst:true instead.
| Name | Required | Description | Default |
|---|---|---|---|
| udid | Yes | Device serial number (UDID) |
Changes observed during successful MCP inspections.
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden and does so well: it discloses that the tool reads the current text length, moves the cursor to the end, and sends exactly that many DELETE keycodes. It does not state what happens if no text field is focused, but the prerequisite mitigates this.
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?
Three sentences, each earning its place: the mechanics, the prerequisite, and the alternative tool. Information is front-loaded and there is no filler or repetition of schema content.
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 one-parameter tool with no output schema, the description is complete: it explains the behavior, the required precondition, and the relevant alternative. Nothing an agent needs to invoke it correctly is missing.
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 only parameter, udid, is already fully described in the schema ('Device serial number (UDID)') with 100% coverage. The description adds no new parameter-level detail, so the baseline 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 clearly specifies a verb ('Clear'), a resource ('focused text field on Android'), and the exact mechanism. It distinguishes itself from device_type and implicitly from ios_clear_text by stating 'on Android'.
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?
It explicitly states the prerequisite: 'Tap the field to focus it first.' It also names the alternative tool and condition: 'use device_type with clearFirst:true instead' when the agent needs to clear and re-type in one call. This is concrete routing guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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