rhino_viewport_image

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

Annotations already indicate this is not read-only (readOnlyHint: false) and not idempotent. The description adds valuable behavioral context: 'no render engine is invoked, just a viewport bitmap dump,' clarifying the lightweight, non-rendered nature. No contradiction with annotations.

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 two sentences, front-loaded with the primary action, and every sentence adds value. No redundant or fluff text.

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?

The description covers the core functionality and distinguishes from render, but it omits details about output (output_path defaults) and transparent background. Since an output schema exists, return values may be documented there, but usage of parameters like transparent_bg is not addressed. Adequate but incomplete for a tool with multiple optional parameters.

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 only for width/height ('Use 0 to inherit on-screen size'), but does not explain other parameters (doc_id, view_name, output_path, transparent_bg). With 0% schema description coverage, the description should compensate, but it fails to cover most parameters.

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 saves viewport pixels to PNG and explicitly positions it as a lightweight alternative to rhino_render_to_file, distinguishing it from that sibling tool. The verb 'save' and resource 'viewport pixels to PNG' are specific and 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 description explicitly says when to use this tool (as an alternative to render) and provides a concrete tip for width/height. It does not explicitly mention when not to use or list all alternatives, but the context is clear enough for typical use.

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