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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely useful behavioral context beyond them: one render returns only the first page of products, Google Shopping exposes no per-product URL so `url` is omitted, `image` is best-effort, and the cost model (one unit per result page; billed like an API request). It stops short of noting rate limits or auth requirements, so not a full 5.

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?

Front-loaded with what the tool returns, then guidance, then caveats and billing in a logical order with no filler. It is dense for a single paragraph but every clause carries information; slightly long for a 6-param 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 no output schema, the description carries the burden and delivers: it enumerates the return fields, discloses the missing `url` and best-effort `image`, states the single-page v1 limitation, and explains the billing units. An agent has enough to call it correctly and set expectations on results and cost.

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 100%, so the baseline is 3 and the schema already documents every parameter. The description still adds value by explaining the interaction between proxy_country and gl (region-specific prices/merchants) and the v1 first-page constraint on max_results, going beyond the field-level text.

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 and resource ('Runs the Google Shopping vertical (udm=28)') and enumerates the returned fields, which cleanly separates it from google_search, amazon_search, walmart_search and ebay_search siblings. An agent can identify what this tool does 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?

The description explains how to target a market (proxy_country/gl) and filter by price, and warns to keep max_results modest due to per-page billing, which implies usage context. However, it never states when to prefer this tool over its many shopping/search siblings (amazon_search, ebay_search, google_search) or any exclusions, leaving routing to inference.

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