Retrieve effective display size and density of an Android screen to map input coordinates correctly, preferring Override size when set for UI automation.
Return effective display size and density: {width, height, density, raw}.
Prefers the Override size (what input coordinates map to) when set.
| Name | Required | Description | Default |
|---|---|---|---|
| serial | No |
| Name | Required | Description | Default |
|---|---|---|---|
No arguments | |||
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose a genuine behavioral trait — that the Override display size is preferred over the physical size — which the agent could not infer from the schema. However, it says nothing about device-selection behavior (serial vs default device) or what happens when no device is connected.
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, front-loaded with the return shape and followed by the one non-obvious behavioral rule. Every sentence earns its place with no filler.
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?
An output schema exists, so return values need not be spelled out, though the description helpfully summarizes them. Given the tool's simplicity (one optional param), the main gap is the undocumented serial parameter and device-targeting behavior; the description 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?
The single optional 'serial' parameter has 0% schema description coverage and is not mentioned anywhere in the description. The description does not explain how serial selects the target device or that omitting it uses the default device, so an agent gets no semantic help for the only parameter.
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?
States a specific verb ('Return') and resource ('effective display size and density') and enumerates the exact returned fields (width, height, density, raw). No sibling tool in the list returns display geometry, so an agent can identify this immediately as the display-metrics tool.
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 phrase 'what input coordinates map to' hints at the tap/swipe coordinate-mapping use case, but there is no explicit when-to-use instruction, no mention of prerequisites (connected device / serial), and no routing to or away from alternatives. The general context is implied rather than stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.