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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety and openness profile is covered. The description adds only that results span multiple merchants, and says nothing about result shape, pagination depth, or whether results can be empty — modest added value against a lower bar.

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 short sentences with the capability statement front-loaded and the alternative routing second. 'Required: query' is mildly redundant with the schema's required list, a small amount of waste in an otherwise tight definition.

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 five-parameter read-only search with no output schema, the description covers what is returned at a high level (product prices and merchant offers) and how to route elsewhere. It omits result format and default country/language behavior, but those are minor for a simple search call.

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%, so query, page, results, country, and language are all documented in the schema itself. The description's only parameter information is 'Required: query', which restates the schema's required array, so baseline 3 applies.

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 — 'Compare product prices and merchants from Google Shopping' — and explicitly names the sibling it is not (amazon_product). An agent can distinguish this from search_walmart/search_ebay without opening any schema, since the scope is Google Shopping price comparison.

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?

Gives an explicit alternative and the condition that selects it: 'For Amazon-only product details use amazon_product.' However, it is silent on the other commerce siblings (search_walmart, search_ebay), leaving the agent to infer how this tool relates to them.

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