Generate animation from the rig

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

Goes well past the annotations: it discloses the pipeline (validated, backed up, verified), the safe default ("dry-run unless apply"), and failure behavior ("Missing bones/slots: suggestions by name, nothing written"). Residual gaps are what happens on a name collision and the role of the `replace`/`allowUpgrade` flags.

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?

Front-loaded with purpose, safety pipeline, and error behavior, then a compact one-clause-per-type catalog; almost nothing is wasted. It is telegraphic to the point of opacity in places ("followers later; restStart"), which costs a little readability but not much length.

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 21-parameter tool with twelve nested option objects, 10% schema coverage and no output schema, the description covers the dispatch dimension but not the per-type option vocabulary an agent needs to populate configs. The docs pointer mitigates this but does not close the gap.

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 description coverage is only 10%, so the description must carry meaning, and it does partially: it maps type values onto intent (breathe path line vs figure8, gaze brow lift/arch/dip, blink eye swaps vs lid bones, onPoses). But the numerous nested numeric options (dart, drift, decay, lag, inertia, hold, gate) are left entirely to the schema, with only a pointer to docs/USAGE.md#generate-options.

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 ("A new animation of one type") and scopes it ("fill only that type's object"), and positions it against spine_add_animation. It does not explicitly say how it differs from spine_derive_animation or spine_transfer_animation, so sibling differentiation is only partial.

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 twelve type fragments act as genuine selection guidance — e.g. "settle: decay after a gesture", "walk: in-place cycle", "lipSync: mouth/jaw from audio" — telling an agent which type fits which situation. What is missing is guidance on when to choose this tool over the generate-adjacent siblings, and no explicit when-not conditions.

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