List Viewports

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

Beyond the readOnlyHint annotation, the description discloses important behavioral nuances: the inclusion of the layout's main viewport with is_main:true, its nature as the tab's pan/zoom state, and the null values for scale/locked on R12 documents. This adds significant context about edge cases and interpretation.

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 concise yet dense, using two sentences to convey the core purpose and critical edge cases. It is well-structured with the main action first, followed by relevant clarifications. No redundant words.

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 tool is a read-only list operation with a rich output schema available. The description adequately covers all necessary context: what is listed, special cases for the main viewport, and behavior on older document formats. There is no missing information for correct invocation.

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 input schema already provides 100% coverage for the single 'layout' parameter with a clear description. The tool description does not add additional meaning beyond the schema, so 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 opens with a specific verb and resource: 'List paper-space viewports' and enumerates the returned attributes (handle, geometry, scale, lock state). It clearly distinguishes itself from sibling tools like viewport_create or viewport_delete by focusing on listing/inspection.

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 usage as a read-only inspection tool but does not explicitly state when to prefer it over alternatives or when not to use it. It lacks direct comparisons to sibling tools such as viewport_set_scale or viewport_lock, so guidance is implicit rather than explicit.

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