Save Screenshot

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

Annotations declare readOnlyHint=false, destructiveHint=false, and openWorldHint=false, so the description is not contradicting them. The description adds minimal behavioral context: it saves to a file, and the schema adds constraints like file extension and scale/maxSize behavior. But the description itself does not disclose side effects, whether it overwrites existing files, or whether it requires a visible screen. With annotations present, the bar is lower, but the description adds little beyond the schema.

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?

The description is a single, clear sentence with no wasted words. It is front-loaded with the action and object. It could add a bit more context, but for its size it is efficient.

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 simple save-to-file tool with 100% schema coverage and no output schema, the description is mostly adequate. However, it does not mention whether the file will be overwritten, whether the screenshot is taken fresh or from the current screen state, or how it relates to mobile_take_screenshot. These are minor gaps given the tool's simplicity.

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 description coverage is 100%, so the schema already documents all four parameters. The description itself does not add parameter-level meaning beyond the schema. Baseline 3 is appropriate because the schema carries the heavy lifting.

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: 'Save a screenshot of the mobile device to a file.' It is distinct from the sibling mobile_take_screenshot, which likely captures/returns the screenshot, while this tool persists it to a file. However, it does not explicitly differentiate itself from that sibling, so it loses a point.

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 implies usage: call it when you need to save a screenshot to a file. The schema's device parameter references mobile_list_available_devices, which gives some context. However, there is no explicit guidance on when to use this versus mobile_take_screenshot, nor any exclusions or alternatives.

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