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

Annotations only tell the agent this is a non-read, non-destructive, closed-world write. The description goes well beyond: it is idempotent, writes only what changed, makes no AI call, and reports residual first-open behavior (random layout / AI copy fill). That is exactly the extra behavioral context annotations cannot convey.

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 content is valuable but packed into long, comma-chained sentences, and it opens with a reference to an editor button rather than a direct verb+resource. It is dense enough that the core action is not front-loaded as sharply as it could be.

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?

With no output schema, the description does carry return-value duty and does state what it would report back ('Says what, if anything, the canvas would still do'). Combined with the mutation effects and idempotency, an agent has enough to call it correctly, though the ambiguity of the 'Continue to design' reference is a minor 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 coverage is 50%; sectionStyle is already documented in the schema as applying only when no section style exists. The description reinforces this ('pin the section style... would otherwise roll one at random') but adds no syntax or format detail, and projectId remains undocumented. 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 names the concrete effects: derive colour roles, pin section style, write band colour and export section list, mark pages built. That is a specific, multi-step operation an agent can distinguish from siblings like set_palette or set_section_style. It never names a sibling explicitly, so it does not reach the top band.

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 clearly states the trigger ('on the first canvas open'), asserts idempotency ('Safe to call again — it writes only what changed'), and notes the no-AI-call condition. It does not compare against the individual setters (set_section_style, set_palette) an agent might otherwise choose, so guidance is clear but not exhaustive.

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