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

Annotations already indicate readOnlyHint=true and openWorldHint=true. The description adds value by noting that cancelled bookings are included and explaining the door_code field lifecycle (null until issued, filled after payment). This provides behavioral context beyond the annotations.

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 three concise sentences, each adding unique value. Front-loaded with the primary purpose, then nuance, then actionable guidance. No redundant or vague phrasing.

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?

Despite no parameters, the description covers use case, sorting, inclusion of cancelled bookings, and door_code behavior. With an output schema present, the agent has sufficient context for correct usage.

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?

There are zero parameters, so baseline is 4 per guidelines. The description does not need to add parameter semantics, but it contributes output field semantics (door_code behavior), which is appropriate given no parameters.

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 clearly states 'list this agent's active/upcoming bookings' with specific criteria (check-out today or later, nearest arrival first). It distinguishes from sibling tools like list_past_bookings via the 'active/upcoming' qualifier.

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?

The description provides explicit guidance: 'Use this tool to give the guest their door code when they ask'. It does not explicitly contrast with siblings, but the context implies alternatives like book, cancel, get_availability, and list_past_bookings serve different purposes.

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