exportFrame

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

With no annotations, the description carries the full burden. It discloses the output format (PNG) and that it returns a base64 preview, which is useful behavioral context, but it omits side-effect details such as whether a file is written to disk by default, where, and any permission requirements for a capture operation.

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?

A single front-loaded sentence that names the verb, resource, formats, and return value with no filler. Appropriately sized, though it is terse enough to leave gaps.

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 five-parameter, file-producing tool with no annotations and no output schema, the description covers purpose and return format but leaves the write side effects, defaults, and sibling routing unaddressed, so it is adequate rather than complete.

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 five parameters. The description reinforces the frame/time distinction and PNG/base64 output but adds no syntax or default information beyond what the schema provides; baseline 3 applies.

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?

States a specific verb (Export) and resource (screenshot/state image of a frame or current time), plus the output format (PNG). It does not differentiate itself from the related sibling exportPreviewVideo, but the purpose itself is unambiguous.

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 dual modes 'specific frame or current time' hint at how the tool is used, but there is no explicit when-to-use / when-not guidance and no reference to exportPreviewVideo as the alternative for motion/preview output.

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