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

The annotations already declare this as a safe read operation (readOnlyHint=true, destructiveHint=false), so the description does not need to restate that. It adds valuable behavioral details: which identity factors are verified, that email is not a verification factor but is matched if supplied, and that results are returned 'in conversation'. No contradictions with 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 tight sentences. The first sentence front-loads the core purpose and output. The second and third provide exact verification requirements and a negative case. Every sentence earns its place; no filler or repetition of schema details.

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 read-only lookup tool with an output schema, this description covers everything needed to call it correctly: required identity factors, accepted verification methods, optional fields, and the negative condition. It also indicates conversational output, so the agent knows what kind of response to expect. The safety profile is already covered by annotations.

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?

Although the input schema has 100% description coverage, the tool description adds crucial cross-parameter semantics: confirmation_number is an alternative to last_four_card combined with check_in_date, and email is optional and insufficient on its own. This combination logic is not encoded in the schema field descriptions, making the description highly valuable for correct invocation.

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 ('look up a reservation'), the resource ('reservation'), and adds a defining characteristic: verification of the guest's identity. It also clarifies the output type ('confirmation number and booking summary in conversation'), which distinguishes it from the sibling tools that act on bookings (book_hotel, cancel_booking, resend_confirmation) and from a generic fetch like get_booking.

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 gives clear context for when this tool is appropriate: the guest must provide full name plus either a confirmation number or card digits with check-in date. It explicitly states a non-sufficient condition ('a name and an email alone will not return a reservation'). However, it does not explicitly name alternative tools or say when to prefer get_booking or another sibling, so it falls short of a 5.

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