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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower; the description still adds the financially relevant guarantee 'Does not spend funds', which matters in a payment-tool family where an agent may otherwise fear a charge. It stops short of describing rate limits or response shape.

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: purpose first, safety constraint second, concrete example last. No filler and no repetition of the title.

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 read-only, single-parameter info tool with no output schema, the description names the returned fields (endpoint, price, network, flow), which is exactly what an agent needs to know it can act on the result. Only minor gaps remain, such as error behavior for an unknown product_id.

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% for the single product_id parameter, and the schema even carries the same example, so the description's example adds nothing beyond it. Baseline 3 applies when the schema does the heavy lifting.

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 (Return) and enumerates the exact resources returned: endpoint, price, payment network, and purchase flow for one product. This clearly separates it from execute_paid_product or the various quote_* siblings, which act rather than inform.

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 clause 'Does not spend funds' implicitly frames this as a preflight/info step taken before a purchase, and the sibling names make the alternative (execute_paid_product) inferable, but no alternative is named explicitly and no 'when to use this instead of X' guidance is given.

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