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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful return-side context (millimetre units, which layout areas are produced) but says nothing about failure modes such as an invalid product_uid or a page_count outside validPageCounts.

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?

A single front-loaded sentence delivers the resource, the unit and the returned areas, followed by the REST path. Nothing is padded, though the endpoint path duplicates information already conveyed by the name and adds marginal value for an MCP caller.

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?

There is no output schema, so the description must carry the return-value burden, and it does so by naming the layout areas and the millimetre unit. Dimensional semantics (e.g. whether bleed is included per side, how wraparound relates to front+spine+back) and error behavior remain unstated, leaving a small 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 100%, so both product_uid and page_count are already documented, including the cross-reference to validPageCounts in gelato_get_product. The description adds no per-parameter syntax or unit interpretation beyond the general millimetre note. Baseline 3 applies when the schema does the heavy lifting.

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?

Names a specific resource (cover dimensions of a multi-page product) and enumerates exactly what is returned: spine, front, back, bleed and wraparound areas, with units. No sibling tool covers cover layout, so an agent can distinguish it immediately 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?

"for designing the cover file" implies the downstream use case and it names multi-page products (photo book, brochure) as the applicable input class, which implicitly excludes single-page/simple products. However there is no explicit when-to-use statement, no prerequisites (e.g. that product_uid must come from gelato_get_product), and no named alternative.

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