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

Annotations already declare readOnly/idempotent/non-destructive, so the bar is lower; the description adds real behavioral context — the specific rejection rules (text overflow, crossing canvas, line-height below 1) and the RESERVED_NAME_DECLARED warning. It also discloses the important limitation that passing validation does not guarantee a successful render.

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-loads the core action and payload types, then enumerates rules compactly in three sentences with zero filler. Slightly dense with rule specifics but every clause carries information.

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?

An output schema exists, so return values need not be explained, and the description supplies the validation rules and a key limitation. Nearly complete for an agent to call it correctly; only workflow placement (when in the pipeline to call it) is left implicit.

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 100%, so the schema already documents both 'json' and 'composition'. The description adds no format or syntax detail beyond restating that patches/designs are accepted, so baseline 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?

Uses a specific verb ('Check/validate') over three named payload types (composition, design, improvement patch) with parenthetical contents, making it clearly distinct from siblings like create_hcmotion. An agent can tell exactly what this operation does without opening the schema.

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?

Implies usage (validate a payload before rendering) and adds the useful caveat 'This is not proof of a successful render', but never states when to choose this over alternatives or any prerequisites/workflow ordering. 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.