Screenshot

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

With no annotations, the description carries the full burden, and it does disclose one important behavior: output is downscaled to save tokens, which warns the agent about reduced fidelity. It does not cover permissions, device selection, or default behavior, leaving meaningful gaps for a capture tool.

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 tight sentences with no wasted words; the primary purpose and the routing condition are both front-loaded.

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 zero-required-parameter, no-annotation, no-output-schema tool, the description adequately covers what it returns (PNG) and when to use it. It falls short on parameter meaning, which is the only other thing an agent needs to call it well.

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 0% and neither parameter (`scale`, `device`) is explained in the description. 'Downscaled' loosely gestures at `scale`, but the default value, units, and the meaning of `device` are left entirely to the agent's inference.

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?

Names the resource (screen) and output format (PNG) unambiguously, and explicitly distinguishes itself from the sibling `look`. The verb is implicit (a noun phrase rather than 'capture the screen'), which keeps it just short of a perfect verb+resource statement.

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?

Gives an explicit routing rule against a named alternative: use this when `look` can't see the target, with concrete examples (games, canvases). The inverse condition is implied strongly enough that an agent knows to prefer `look` normally.

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