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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds the GET endpoint and the return type ('booking object'), which is useful but does not cover auth, error behavior, or default field set details.

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 compact and front-loaded with the primary action. The endpoint reference and fields guidance earn their place, though the phrase 'booking object' adds only mild additional value.

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 read operation with full schema coverage and a readOnlyHint, the description is sufficient for correct invocation. It states what is returned and how to narrow fields; the lack of an output schema is partially mitigated by the explicit 'returns the booking object' statement.

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 bookingId and fields are already well documented. The description reinforces that fields controls returned fields but adds no meaning beyond the schema.

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 ('Fetch'), a specific resource ('a single booking'), and the key qualifier ('by id'). This clearly distinguishes it from list_bookings, which retrieves multiple bookings, and from create/update/cancel variants.

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 clear context: use this tool when you need a single booking by its ID. It does not explicitly name alternatives or exclusions, but the singular 'by id' framing implies the right condition for selection.

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