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

The annotations already signal this is a non-read-only, non-idempotent mutation, and the description adds important behavioral context: the PRICE_CHANGED status flow, the accepted_terms_digest retry pattern, and the returned fields. It could disclose lock duration or side effects of repeated calls, but what is included goes beyond the annotations usefully.

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 sentences with no filler. It front-loads the core action, then lists the important return values, then covers the two critical conditional flows (PRICE_CHANGED retry and budget-overrun guard). Every sentence earns its place.

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 compensates by listing key return fields (prebook_id, total, cancellation, taxes, terms_digest) and the status value that drives retry behavior. It is reasonably complete for an agent to invoke and interpret the common paths, though it does not cover lock expiry or failure modes.

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 meaningful parameter semantics by explaining that accepted_terms_digest must be set to the latest terms_digest when retrying after PRICE_CHANGED, and by linking prebook_id to start_booking. This is genuine extra guidance 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?

The description opens with a specific verb and resource: "Verify and lock the quoted rate with the supplier before payment." It clearly distinguishes itself from siblings by positioning it as the pre-payment, pre-start_booking locking step and by noting it returns prebook_id required for start_booking.

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 provides clear sequencing context by stating prebook_id is required for start_booking, and it explicitly gives a when-not-to-call rule for budget overages with required user confirmation. It does not explicitly name all alternatives, but the budget guard and downstream dependency are strong practical guidance.

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