screenshot

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

No annotations are provided, so the description carries the full behavioral burden. It usefully discloses the return behavior (image path plus inline image, with returnImage: false to disable), but it does not mention that the tool writes a PNG file to disk by default, how overwrite behavior works, or any permission/failure considerations. The schema covers those details, but the description alone gives only partial behavioral context.

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 tightly written sentences with zero waste. The core purpose is front-loaded, followed by the important return behavior and the key opt-out parameter.

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?

Given the rich input schema and no output schema, the description is largely complete for correct invocation: it states the capture target categories and explains what is returned, including inline image behavior. It is slightly thin on side effects and sibling selection guidance, but the schema fills most structured 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?

Schema description coverage is 100%, so the schema already documents all seven parameters thoroughly. The description adds only a small amount beyond the schema by noting that returnImage: false disables inline image return. Baseline 3 is appropriate because the schema does 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 specific verb and resource: 'Capture a single still frame (PNG) of a target', and enumerates the target types (full screen, monitor, window, region). It distinguishes itself from recording siblings by emphasizing 'single still frame', but it does not explicitly name or contrast with alternatives such as sample_frames or start_recording.

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?

Usage is implied by the purpose: use this when a one-off screenshot is needed. However, there is no explicit when-to-use/when-not-to-use guidance and no mention of alternatives like sample_frames, zoom, or recording tools. The target options describe input format, not when this tool should be selected over siblings.

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