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 goes beyond them with genuinely useful billing semantics — the maximum cost is held upfront, you are charged only for what returns, and failed calls are free — which materially affects how an agent should call it. It also enumerates the returned fields.

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?

Three tight sentences, each doing distinct work: purpose, return shape, and cost model. No filler, and the most decision-relevant information (what it extracts) is front-loaded.

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, listing the returned fields and the billing model is a real contribution, and annotations cover the read-only profile. However, for a 6-parameter tool with near-zero schema coverage, the description leaves four parameters unexplained, so an agent cannot confidently set locale, freshness, or location options.

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 only 17% (only idempotency_key is documented), yet the description explains no parameters at all. The meaning of gl, hl, fresh, and location is left entirely to inference, and the retry/idempotency behavior described in the schema is not reinforced or clarified in the description.

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 (extract) and resource (Google Shopping carousel listings) with the query domain (e-commerce/product queries) named. It is clearer than most siblings, though it does not explicitly differentiate itself from the similar-sounding extract_products or google_serp.

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 e-commerce and product queries" gives implied context for when this tool fits, but there is no explicit guidance on when to prefer it over extract_products, extract_local_places, or google_serp, and no exclusions. Usage must be inferred.

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