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

Annotations only say readOnly=false, idempotent=false, destructive=false; the description adds genuinely new behavior: a 10-minute lock window, zero cost, and the exact return payload (quoteId, USDC price, delivery contents). It stops short of saying whether calling twice invalidates or stacks quotes, which matters given idempotentHint=false.

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, front-loaded with what it does and how long the lock lasts, then the return value, then the safety instruction. Every sentence carries distinct information with no repetition of the schema.

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 9-parameter, non-idempotent tool with no output schema, the description still conveys cost, lifetime, and return contents, and the parameter variety is fully covered by the schema. The one gap is quote lifecycle after expiry or on repeated calls, which the agent must guess.

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 all nine parameters (including the payer/sender KYC and fields object) are already documented in the schema. The description adds only the generic notion of "the recipient" and no field-level guidance, 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?

"Lock a price (10 minutes) for one purchase" states a specific verb (lock), resource (price) and scope (one purchase), and the 10-minute duration immediately separates it from the sibling buy tool. An agent can tell this is a pre-purchase price-lock, not the purchase itself, 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 gives a concrete workflow rule — "ALWAYS show the human the price and the recipient before buying" — which implies quote comes before buy and gates the human confirmation step. It does not explicitly say when not to use it (e.g. reuse an unexpired quote vs. re-quote) or name buy as the follow-up tool by name.

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