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

Annotations already declare readOnlyHint=true and destructiveHint=false; description adds the specific non-actions (does not create checkout, cart, order, etc.) and frames it as 'read-only detail retrieval', reinforcing the idempotentHint. It doesn't mention rate limits or auth beyond the UCP profile mention which is in schema, but adds enough context beyond annotations.

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 description is a single, front-loaded paragraph (approximately 60 words) that states the purpose, the when-to-use, and the boundary of what it does not do. Every sentence adds value and there is no redundancy with the schema.

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?

Given there is an output schema and the annotations disclose read-only/idempotent behavior, the description covers the essential prerequisites (requires 'meta.ucp-agent.profile', 'catalog.id') implicitly via schema, and explicitly states the side-effect-free guarantee. It doesn't explain error conditions or rate limits, but those are not required for high completeness. The missing negative guidance on when NOT to call it (e.g., for multi-product or mutation) is implied by 'exactly one selected product' and the non-actions.

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?

The schema has thorough parameter descriptions (100% coverage), including the purpose of each field and clarifications like 'no purchase occurs' and 'never authorizes billing.' The tool description adds little beyond pointing to the schema's 'exactly one selected product' requirement and id source. Given the high schema coverage, the description doesn't need to add much; baseline of 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?

Description states a specific verb ('read-only detail retrieval') and resource ('exactly one selected product'), and explicitly distinguishes from sibling tools by naming them and the sequencing ('Call after search_catalog or lookup_catalog'). It also enumerates what it does NOT do (create cart, order, etc.), making its scope unmistakable.

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?

Provides explicit when to use: after search_catalog or lookup_catalog, when full current price, availability, machine endpoint, and checkout-handoff metadata are needed. Also specifies a clear when-not by listing side-effects it does not produce (create checkout, cart, order, payment, credential, merchant state).

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