Stop an active screen recording on an Android or iOS device and save it as an MP4 file to a specified absolute local path.
Stop screen recording and save the file. Use an absolute path for localPath to ensure you can find the file.
| Name | Required | Description | Default |
|---|---|---|---|
| deviceId | Yes | ||
| platform | Yes | ||
| localPath | Yes | Local destination path for the .mp4 file (e.g. C:\Users\...\recording.mp4) |
Changes observed during successful MCP inspections.
v1.1.4Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of explaining behavior, and it does disclose the primary side effect: stopping the recording and writing the file to localPath. However, it omits preconditions (an active recording), overwrite behavior, and what the tool returns.
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 with no filler; the primary action is front-loaded and the path caveat is a practical, necessary addition. 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?
For an unannotated tool with no output schema, the definition is too thin: it does not mention that a recording must already be active, what the call returns, or how deviceId and platform relate to the operation. An agent would have to guess several preconditions and confirmation details.
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?
Only localPath receives extra semantic guidance ('absolute path'), and that parameter is already described in the schema with a format and example. deviceId and platform are left to inference, and with schema description coverage at only 33%, the description does not compensate for the undocumented required parameters.
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 names a specific verb and resource ('stop screen recording') and states the outcome ('save the file'), so an agent immediately knows the core action. It is clearly distinguishable from the sibling start_recording even though that sibling is not mentioned.
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?
There is no explicit 'use when' or 'use instead of' guidance; the intended pairing with start_recording is only implied by the tool name and sibling list. The absolute-path sentence is a parameter instruction, not tool-selection guidance.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.