get_viewport_screenshot

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

Annotations only mark readOnlyHint=true, so the description carries most of the behavioral burden. It adds valuable context: GPUOffScreen usage, why it matters (fixes black screens when window is not foreground), fallback to window grab, and the result fields. This gives an agent useful expectations 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?

Three short sentences, with the core purpose first, then the bug/fix context, fallback, and return shape. No filler; each sentence contributes behavior or output information.

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 read-only screenshot tool with three optional parameters and no output schema, the description covers purpose, method, fallback, and return values. However, it leaves parameter semantics undocumented and gives no guidance on when to choose this over camera_render or render_object_preview, so it is adequate but not fully 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 coverage is 0%, and the description does not explain format, filepath, or max_size. It only names filepath in the return object, which is ambiguous because filepath is also an input parameter. The names and defaults provide some hints, but the description adds no parameter-level meaning.

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 opens with a specific verb and resource: 'Screenshot of 3D viewport...' and closes with the exact return shape ({success, width, height, filepath, method}). This distinguishes it from rendering/export siblings such as camera_render or render_object_preview, which target camera or rendered output rather than the live viewport.

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 phrase 'Screenshot of 3D viewport' implies the obvious use case, but the description never states when to prefer it over alternatives or when not to use it. The fallback note ('Falls back to window grab if GPU unavailable') is a runtime behavior, not usage guidance. No exclusion conditions or alternative tool names are mentioned.

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