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

Beyond the readOnly/openWorld annotations, it discloses determinism, fail-closed validation, reduced-motion enforcement, performance reporting, and the exact return shape ({ok, js, css, report} or {ok:false, errors}). No annotation contradiction exists.

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?

Four dense sentences contain no filler, and the critical operational constraints (cost/local option, validation, output) are each conveyed once. The return contract is compactly and clearly stated.

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 deterministic compiler tool, the description covers prerequisites, local alternative, validation semantics, output artifacts, and error form even without an output schema. An agent has enough to select and invoke it correctly.

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 100%, so the schema already documents spec and specName. The description does not add parameter-level detail beyond the schema, which is acceptable but not value-adding; the baseline of 3 applies.

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 names a concrete action (deterministically compiles) and resource (MotionSpec) with a specific output (vanilla-GSAP JavaScript and CSS). It clearly differs from sibling tools like motion_validate or motion_audit by stating it produces code, not just validation or analysis.

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?

It gives explicit prerequisites (hosted Dev Key/Agency plan vs free local npx command) and states fail-closed behavior, which tells an agent when the compile will fail. It does not explicitly name sibling alternatives or say when to prefer motion_validate/audit, so it stops short of full routing guidance.

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