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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds that results are full UCP records obtained in one call, which is useful, but it does not go deeper into error handling, idempotency edge cases, or any limitations beyond the schema's maxItems.

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?

Two sentences with no filler. The core capability and constraint are front-loaded, and the sibling pointer is a separate, easy-to-parse clause. Every word earns its place.

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 single-parameter lookup tool with full schema coverage and comprehensive annotations, the description is nearly complete. It defines the return payload as 'Full UCP product records' and gives the single-product alternative. It is slightly opaque about 'UCP' and error behavior for invalid ids, but these are minor gaps given the tool's simplicity.

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%: the single 'ids' parameter is fully documented as product ids or handles with min/max items. The description only repeats 'by id or handle' and 'up to 6', adding no new semantic value beyond the schema.

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 (look up), resource (Full UCP product records), and scope (up to 6 products by id or handle in one call). It explicitly names get_product as the single-product alternative, so it is clearly distinguished from siblings.

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 description provides an explicit routing rule: use lookup_catalog for batch lookups up to 6 products, and get_product when you need one. This gives the agent a clear decision criterion without needing to inspect other tool definitions.

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