Screenshot

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The `readOnlyHint: true` annotation already covers the safety profile. The description adds useful behavior by noting the screen is captured as PNG and can optionally be written to file, but it omits details such as device-online requirements or return format.

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 concise sentences, front-loaded with the core action and followed by the optional file-saving behavior. There is no redundant or filler text.

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 two-parameter read operation with full schema coverage and a `readOnlyHint`, the description is largely complete. It clearly states the output is a PNG and supports optional saving, though it could better differentiate from the sibling `ide_screenshot` tool.

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 parameter meanings are already documented in the input schema. The description mentions the optional file-save behavior, which maps to `savePath`, but adds no syntax or format details beyond the schema.

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 verb and resource: capture the device screen as a PNG image, plus optional file saving. It is specific enough for an agent to understand the action, but it does not distinguish this from the sibling `ide_screenshot` 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?

There is no guidance on when to use this tool versus `ide_screenshot`, `ui_dump`, or other screen-related siblings. The only implied usage is the basic action itself, with no exclusions or conditions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.