List Viewports

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

Beyond the readOnlyHint annotation, the description discloses important edge-case behavior: the main viewport is included with is_main: true, it represents tab pan/zoom state rather than a drafting viewport, and scale/locked are null on R12 documents rather than fabricated. This is exactly the kind of behavioral context annotations cannot convey.

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 compact and front-loaded: the one-sentence purpose comes first, followed by two denser but necessary caveats about main viewport semantics and R12 nulls. Every sentence earns its place with no repetition of schema fields.

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 filtered listing tool with a single documented parameter, a readOnlyHint annotation, and an output schema present, the description covers all non-obvious behaviors: inclusion of the main viewport, its special nature, and legacy-format null handling. Nothing critical is missing.

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 sole parameter `layout` is already fully documented in the schema with its default and meaning ('Empty covers every sheet'). The description adds no further parameter-level detail, so the schema carries the full burden; baseline 3 is appropriate.

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 uses a specific verb and resource: 'List paper-space viewports' followed by the concrete fields returned (handle, geometry, scale, lock state). This clearly distinguishes it from sibling mutation/viewport tools like viewport_set_scale, viewport_lock, and viewport_delete.

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 tool's purpose as a read-only listing operation is clear from the first line and reinforced by the parameter description. However, it does not explicitly name sibling alternatives or state when not to use it; the guidance is implied rather than explicit.

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