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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description earns credit for adding the 50-id batch ceiling and the not_found response for ids outside the priced subset, but says nothing about authorization on the ucp-agent profile or response pagination.

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 substance is front-loaded but delivered as one dense run-on sentence salted with protocol metadata ('version 2026-08-25', 'dev.ucp.shopping.catalog.lookup') that costs tokens without helping an agent choose or call the tool.

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 an output schema present, return details are largely optional, yet it still sketches the result shape (products with claim_status) and the failure mode. Parameters are covered, leaving only the context/filters sub-fields and the contradictory 'required' framing of meta as gaps.

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 0% and both parameters are untyped nested objects, so the description carries the full burden — and it does: it names meta {'ucp-agent': {profile}} as required-ish and enumerates catalog fields (ids, context, filters) plus both id formats and the 50-item limit. It stops short of explaining context and filters.

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 concrete verb+resource: a UCP catalogue lookup that resolves supplied product ids (GTIN) or variant ids (<market>:<gtin14>) into product rows with claim_status. The id-based framing implicitly separates it from search_catalog, but no sibling tool is named explicitly.

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?

Usage is only implied: you supply ids, up to 50, and get rows back. It never says when to pick this over search_catalog, get_product, or get_item, nor what prerequisites exist for the meta profile beyond calling it 'required'.

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