rig_preview

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

No annotations, so the description must carry the load, and it does disclose non-obvious behavior: parts claim pixels in list order, leftovers form an implicit 'rest' part, and the preview is rendered with tints plus white pivot dots. It omits whether the tool mutates document state or errors on an invalid rig, which is a meaningful gap for a nested-object tool.

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?

Dense but front-loaded: the purpose and observable outputs come first, then the rig grammar. The inline pseudo-schema is terse and earns its space, though the run-on structure makes it slower to scan than a bulleted shape.

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 4-parameter tool with a deeply nested object, no annotations, and no output schema, the rig grammar is well covered but the frame/layer targeting and the mutation-vs-read nature are left undefined. An agent could construct a rig but not confidently pick frame or layer values.

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%, so the description must document everything, and it does an above-average job on the complex `rig` parameter — mask variants (rect/polygon/rows/colors/union/minus), pivot, parent, z, and the overlap flag are all explained. However `path`, `frame`, and `layer` (half the parameters) are never mentioned, so compensation is partial.

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+resource: 'Check a rig before animating', and enumerates what the preview reveals (tinted pixel assignment, white pivot dots, pixel counts, bounding boxes). It is distinguishable from animate_rig and check_animation by being a static diagnostic rather than a motion evaluation, though it never names those siblings.

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?

'Check a rig before animating' gives clear situational context — this is a pre-flight validation step. There are no explicit exclusions or named alternatives (e.g. lint, check_animation) telling the agent when to pick a different diagnostic.

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