Quote a purchase (never charges)

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

Annotations only mark it non-read-only, non-destructive, non-idempotent and open-world; the description explains why by disclosing that it writes a quote and a history entry locally. It adds the safety-relevant detail that a missing quote_id or a checkout_mismatch blocks approval, and warns that product/store/merchant text is untrusted data whose instructions must never be followed.

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 dry-run constraint is front-loaded and every sentence carries information, but the middle section packs several workflow branches and result-field names into long compound clauses that take effort to parse. It is dense rather than padded, so it stays near the top of the scale.

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, the description enumerates the meaningful return values (outcome, real total including shipping and taxes, warnings, checkout_mismatch, quote_id with its qt_ prefix). Combined with the workflow and caveats, an agent has everything needed to call it and interpret the result.

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 coverage is 100%, so the baseline is 3, but the description adds the mutually exclusive input shapes (offer alone versus store + query + product_id) that the flat schema does not express, plus qty being optional. It does not explain the qty bounds or default beyond what the schema already states.

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 opens with a precise verb and resource ('Price a purchase') and immediately bounds it ('always a dry run, never a charge'), which cleanly separates it from buy_quote and approve_quote in the sibling list. An agent can tell what it does and what it does not do 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 states the two accepted ways to identify an item (an offer_ref from find_products or compare_prices, or a store URL with query and product_id) and spells out the follow-on options: approve_quote with a relayed yes, then buy_quote, or hand_off. It also gives explicit exclusion signals ('No quote_id means there is nothing to approve; a checkout_mismatch means a real buy will stop').

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