Render Viewport

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful context beyond that: it discloses the return payload (base64 bytes plus metadata) and that the MCP server surfaces it as an image content block, plus the camera-repositioning side effect of the view parameter.

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 tight sentences: capability, then the key parameter decision, then the return contract. Front-loaded and zero waste.

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?

No output schema exists, and the description steps in to describe the return value and delivery mechanism, which is exactly what is needed. Annotations cover the safety envelope. Only minor gap is that per-parameter detail for width/height is left implicit.

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 50%: 'fit' and 'view' are documented in the schema, and the description reinforces 'view' semantics ('current' preserves vs canonical reposition). Width and height carry no description in either place, though their min/max bounds make them self-evident. Adds meaning for one parameter but does not fully compensate for the gap.

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 (Capture), resource (active viewport), output format (PNG), and purpose (visually verify the model). This clearly distinguishes it from siblings like export_view_sheet or export_stl, which produce different artifacts.

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?

Explains the choice condition between passing a canonical view to reposition versus 'current' to keep it as is, and frames the overall use case (visual verification). It does not name an explicit alternative sibling, so it falls short of a 5.

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