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

Annotations already flag this as destructive and non-idempotent, and the description earns its keep by explaining exactly what the destructive behavior destroys ('frees the old place') and under what conditions a change is rejected (quantity change on online-paid bookings, cutoff timing). This is the kind of context annotations cannot express.

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, each carrying a distinct constraint: purpose and eligibility first, then the value source, then the paid-booking restriction, then the timing cutoff. No filler and no repetition of schema text.

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 destructive mutation with no output schema, the description covers eligibility, value sourcing, constraints, and timing, which is nearly everything needed to call it correctly. The remaining gap is the partial-update semantics (must slot or quantity be supplied, can both be set at once).

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; the description adds real meaning beyond it by constraining when `quantity` is even usable (not for online-paid bookings) and pointing `slot` at get_availability as the value source. It doesn't clarify whether slot and quantity can be changed in the same call or what happens if neither is supplied.

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 (change) and the exact fields it can change (slot or quantity), plus the eligible booking states (pending, awaiting_payment, confirmed). This is clearly distinguishable from siblings like cancel_booking and request_booking without opening any schema.

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 the trigger condition ('when the customer asks to'), the authoritative source for the slot value (get_availability), and an explicit alternative path: for online-paid bookings, cancel and rebook instead of changing quantity. It also names the timing boundary ('same cutoff as online cancellation'), so when-not-to-use is covered too.

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