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

Annotations already declare readOnlyHint=false, destructiveHint=false, idempotentHint=true; the description adds behavior the annotations cannot: payment is collected by the property and the agent must never ask for card details, plus the returned booking reference. It does not mention duplicate-booking behavior despite idempotentHint=true, nor what happens if the rate is no longer available.

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?

Four short sentences, front-loaded with the action, then the gate condition, then the payment safety rule, then the return value. No filler and nothing repeated from 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 non-idempotent-looking booking mutation with no output schema, it covers the critical agent-facing concerns: confirmation gating, payment handling and the return value. The remaining gap is the provenance/format of rate_key and failure handling, which an agent would still have to 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 0%, so the description must carry parameter meaning. It meaningfully explains traveller_confirmed (set true only after explicit confirmation of a specific list of items), but rate_key — the one non-obvious identifier — is never explained, nor are the guest contact fields or special_requests.

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 and resource ('Confirm a booking') and distinguishes itself by describing the outcome ('Returns the booking reference'), which clearly separates it from read-oriented siblings like check_rate, search_hotels and get_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?

Gives an explicit, hard precondition: only call after the traveller has confirmed hotel, dates, room, price, cancellation policy and payment terms, with the traveller_confirmed flag. It stops short of naming a prerequisite sibling (e.g. that rate_key comes from check_rate) or naming when-not-to-use cases, so it is clear but not fully routing.

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