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

Annotations already declare readOnlyHint, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds an important behavioral caveat: it returns the cheapest listing per store for the query, not necessarily the identical SKU, which prevents incorrect assumptions about exact-product comparison.

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 three tight sentences: primary behavior first, then the key caveat, then workflow guidance. Every sentence adds useful information and nothing is wasted.

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 the annotations, full schema coverage, and an output schema, the description provides everything needed: scope, return shape, a critical semantic caveat, and integration guidance with sibling tools.

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 both parameters (query and brand) are already documented in the schema. The description reinforces that this is a product-query tool but adds no further syntax or usage detail for the brand filter, so baseline 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?

The description states a specific verb and resource ("Compare prices"), names the retailer scope, and specifies the return shape: cheapest listing per retailer sorted by price. It also distinguishes itself from search_products by saying it can be used after search or standalone, so the agent can identify its role 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?

It explicitly gives workflow guidance: "Use after search_products or standalone; then render_product_results to display the offers as cards." This tells the agent both preceding and following tools, making invocation sequencing clear.

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