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

Annotations declare readOnlyHint=true and destructiveHint=false, and the description reinforces this with a crucial disclosure that a tool named 'start_booking' otherwise obscures: 'Does not book, hold or charge'. It adds process rules (never ask for card details) and documented error outcomes with alternatives, which go well beyond the structured hints.

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?

The prerequisite is front-loaded, followed by what is returned, what the agent must do with it, the safety boundaries, and error codes. Each clause carries distinct information with no filler.

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?

An output schema exists, yet the description still names the key returned fields and the guest-facing next step, and it covers failure modes for a 9-parameter tool. An agent has everything needed to invoke it correctly and act on the result.

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 is already documented including the house/room_id/room_type combination and rate_id provenance. The description's parameter sentence largely restates that, though 'as returned' mildly reinforces that values must be passed through unmodified.

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 description states a specific verb and output: it 'Checks again and returns a summary (room, dates, guests, total EUR) and checkout_url'. It is clearly distinguished from its prerequisite sibling check_availability by framing itself as the step 'After check_availability and the guest's choice'.

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 an explicit prerequisite (check_availability plus the guest's choice), tells the agent what to pass and where those values come from ('as returned'), and prescribes the follow-up flow: 'Show the summary, then give the guest checkout_url'. It also names when the tool cannot proceed, via the NOT_AVAILABLE and BOOKING_NOT_YET_ONLINE error cases.

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