Reads indexed UI elements from an Android phone to capture a UI snapshot and provide element IDs for follow-up actions.
Read indexed UI elements. IDs are valid only with the returned snapshot.
| 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?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint, and destructiveHint=false, so the safety profile is covered. The description adds one genuinely useful behavioral trait: the returned element IDs are ephemeral/valid only against the snapshot that produced them. It says nothing about snapshot lifetime or what happens on a stale ID, so it goes beyond annotations only modestly.
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 and the core action front-loaded. Slightly stingy for a tool with an undocumented parameter, but structurally clean.
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 needn't be explained, and the ephemeral-ID caveat is a valuable addition. Still, the concept of a "snapshot" is never defined (how it is obtained, how long IDs remain valid), and the sole parameter is left entirely undocumented, leaving meaningful gaps.
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?
There is one parameter (serial) with 0% schema description coverage, so the description carries the full burden of explaining it — yet the description never mentions the parameter at all. An agent cannot learn from either source what serial does or whether it is required.
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?
"Read indexed UI elements" gives a specific verb and resource, and the word "indexed" hints at the snapshot-scoped nature. However, it does not distinguish itself from the sibling phone_find_elements, which reads as a similar discovery operation, so sibling differentiation is absent.
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 offers only a validity constraint ("IDs are valid only with the returned snapshot") rather than any when-to-use guidance. It never says when to call phone_observe versus phone_find_elements, phone_screenshot, or phone_status.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.