compare_products

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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely useful non-annotation context: no batch endpoint, ~3 calls (~6 s) per item, and that failed items are returned with a reason rather than aborting the whole 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?

Two tight sentences: the return contract first, then the cost/failure behavior. No filler, and the most decision-relevant facts are 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?

An output schema exists, so return shape need not be spelled out, yet the description still gives the fields and the partial-failure contract. Combined with the latency disclosure, this is nearly complete; only the when-to-use-vs-siblings angle is absent.

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 (city, products) are already documented, including the city default and FIAS-id format. The description restates the 10-item cap already enforced by maxItems, adding no new semantics beyond the schema.

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+resource (compare products side by side) and enumerates exactly what is returned: variant, both prices, stock, line rating, cheapest delivery. This clearly distinguishes it from get_product (single item) and search_products (discovery).

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 'up to 10 items' cap and the cost note imply a bounded, deliberate use case, but the description never states when to prefer this over calling get_product repeatedly, nor any exclusions. Usage is implied through the cost/latency remark rather than explicit routing guidance.

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