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

The annotations already declare idempotentHint=true and openWorldHint=true, but the description adds substantial context beyond them: the dual confirmation/request outcome, the fact that the customer is emailed, that the response carries a `manage.token`, and the retry contract (same key returns the first booking with the same token rather than creating a second). That is genuinely useful operational detail, and nothing contradicts the annotations.

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 sentences, all load-bearing: outcome first, then the response contract, then the confirm-before-calling rule, then the idempotency mechanics. Nothing is padding, and the most decision-relevant facts are front-loaded.

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?

There is no output schema, and the description fills that gap by describing what the answer reports (confirmation vs. request, next steps, manage token). For a six-parameter, nested-object tool with full annotation coverage, an agent has everything needed to call it correctly.

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%, including a very detailed `idempotency_key` description, so the schema already carries the parameter burden and 3 is the baseline. The description's key advice ("choose a new random one for each booking (a UUID without hyphens) and send the same one to retry after a timeout") largely restates the schema rather than adding new syntax or constraints.

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 opening sentence names a specific verb ("Book") and resource ("one of the open times for the customer") and immediately states the outcome: it is either confirmed at once or arrives as a request for approval. This is plainly distinguishable from the read-only siblings (find_times, get_booking, get_business) and from cancel_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 gives a clear precondition ("Confirm the service, the time and the customer's details with the customer before calling it") and points at the `manage.token` for later checking or cancelling, implicitly routing to get_booking/cancel_booking. It does not explicitly say the start time must come from find_times or when not to call it, so the guidance is strong but not exhaustive.

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