get_viewport_screenshot

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

With no annotations provided, the description must carry the burden of behavioral disclosure. It does state the return type ('Returns the screenshot as an Image') and implies a read-only read of the viewport, but it does not explicitly mention lack of side effects or potential requirements like an open 3D viewport. This is adequate but not rich.

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 efficient and front-loaded with the main purpose. The parameter list is somewhat redundant with the schema but still adds useful detail. However, the inaccuracy regarding the default value prevents a perfect score, as every sentence should be accurate.

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 screenshot tool, the description covers the core action, parameters, and return type. But it lacks usage guidance, caveats about viewport availability, and has the default discrepancy. Given the lack of annotations and output schema, the description is adequate but has clear 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?

The description adds meaning to both parameters (max_size and user_prompt), but it contains a factual error: it states max_size default is 800 while the schema says 1000. This contradiction makes the parameter information misleading. Despite explaining semantics, the error undermines reliability, so it does not sufficiently compensate for the 0% schema description coverage.

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 clearly states the tool's function: 'Capture a screenshot of the current Blender 3D viewport.' This is a specific verb+resource combination that distinguishes it from siblings like get_scene_info or get_object_info, which provide textual information rather than visual capture.

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 the tool should be used when a visual representation of the viewport is needed, but it does not explicitly state when to use it versus alternatives, nor does it provide exclusions or prerequisites. The context is clear but there is no direct guidance on selection among sibling tools.

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