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

Annotations already declare non-readOnly, non-idempotent, open-world, non-destructive. The description adds real behavioral context beyond that: a WhatsApp verification code is sent to the phone, and the slot is held only after confirm_booking. It stops short of describing failure/retry behavior or code expiry, but the essential flow is disclosed.

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 tight sentences, all load-bearing: the core action, the mechanism, the finalization rule, and the sibling alternative. Front-loaded with the essential distinction (booking without access) before the routing advice.

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 7-param mutation tool with no output schema, the description covers the key flow (WhatsApp code, then confirm_booking) so the agent knows this call alone does not finalize a booking. It does not hint at what the response returns (e.g., a token needed for confirm), a minor gap but not essential to correct invocation.

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 every parameter (kind enum, slug, time, date, phone, names) is already documented in the schema, including the date-only-for-services rule. The description adds no parameter-level syntax or format detail beyond what the schema provides, 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?

States a specific action (request a booking without account/login) and the mechanism (sends a WhatsApp code to the phone). It explicitly distinguishes itself from siblings confirm_booking (reservation not final until then) and book (for users with a session), so an agent can route correctly without opening schemas.

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?

Explicitly gives the when-to-use condition (no account / no access) and names the alternative with its selecting condition ("Se la persona ha già una sessione usa book"). It also clarifies that the booking is only finalized via confirm_booking, so the agent understands this is a two-step flow.

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