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

The description adds useful behavioral context beyond the destructiveHint annotation: it discloses the side effect of adding a note under the acting account and states which booking states are ineligible. It does not clarify permissions, reversibility, or response behavior, but it adds meaningful operational detail.

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 description is front-loaded with the core action, then adds side-effect context, eligibility restriction, and implementation endpoint in three compact sentences. Every sentence contributes useful information without padding.

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 simple two-parameter tool with no output schema, the description covers purpose, restrictions, and side effects adequately. It could more fully describe what a successful check-in/out returns, but the core context an agent needs is present.

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 both parameters are already documented in the schema. The description does not add new semantic detail about booking_id or action beyond what the schema provides, making the baseline score of 3 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?

The description states a specific action and resource: marking a guest as arrived or departed for a booking. It is immediately distinguishable from siblings like update_booking_status or add_booking_note, which do not describe check-in/check-out semantics.

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 clear usage context ('mark a guest as arrived or departed') and a when-not condition ('VOID and cancelled bookings cannot be checked in or out'). However, it does not name a sibling alternative or explain when to prefer update_booking_status over this tool.

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