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

Annotations already cover read/write and idempotency, but the description adds important behavior: no credit card needed when paying at the property, deposit links for stays above the deposit limit, and a 1-hour payment deadline. It also states that the guest receives a confirmation email, which is useful post-call context.

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 sentences, front-loaded with the action, followed by payment behavior and then the critical call preconditions. The parenthetical is dense but earns its place by covering deposit exceptions and timing.

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 booking mutation with annotations covering safety/idempotency and a fully documented schema, the description supplies the missing operational context: prerequisites, payment/deposit behavior, guest confirmation requirements, and confirmation email outcome.

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 all parameters are already documented. The description adds some precondition context around apartment, dates, guests, and contact details, but does not materially enrich individual parameter semantics beyond what the schema provides; baseline 3 is appropriate.

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+resource ('Book an apartment for the guest') and clearly distinguishes booking from availability/property-info siblings. The prerequisite reference to check_availability reinforces what this tool is and is not for.

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 says to call only after check_availability and only after the guest has confirmed apartment, dates, guests, total price, and contact details. This gives clear preconditions and effectively routes the agent away from premature booking.

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