Tap a mobile screen at raw x,y coordinates to simulate user taps in UI tests. Use when a precise screen position needs interaction, not an element selector.
Tap at raw screen coordinates (x, y). To tap an element by selector, use the 'tap' tool.
| Name | Required | Description | Default |
|---|---|---|---|
| x | Yes | X coordinate to tap | |
| y | Yes | Y coordinate to tap | |
| device_id | No | Target device ID. If omitted, uses the default device. |
Changes observed during successful MCP inspections.
v3.8.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries behavioral disclosure on its own. It clearly indicates the tap is at raw screen coordinates and does not involve element lookup, but it omits details like coordinate origin/units and out-of-bounds behavior.
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?
Two short sentences deliver the core purpose first and the alternative second, with no redundant wording.
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 and the schema documents all parameters, but there is no output schema or behavior notes about coordinate system or failure cases. The description is adequate for basic invocation but leaves a few operational details implicit.
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%, so the description doesn't need to repeat parameter definitions. It adds the useful clarification that x/y are raw screen coordinates rather than element-relative, though it does not specify units or origin.
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 states a clear action ('Tap') and a specific resource ('raw screen coordinates'), distinguishing this tool from selector-based tapping. The explicit contrast with the 'tap' tool makes its purpose unambiguous.
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 tells the agent when not to use this tool: to tap an element by selector, use the 'tap' tool instead. This gives a direct routing rule from raw-coordinate tapping to selector-based tapping.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.