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

Annotations already declare readOnlyHint=true, and the description is consistent, explicitly stating "Informational only" and "nothing is shown or changed in this chat." It goes well beyond annotations by disclosing auth requirements, the guest-session restriction, and the non-obvious side effect of the `email` fallback (a sign-in link is emailed, result carries `magicLinkSent: true`) — behavior an agent could not infer from structured fields.

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?

Front-loaded with the useful part, but it is one dense block with nested parentheticals, including a credit-line settlement endpoint reference that is tangential to reading one booking. Splitting the required-ID, session, and fallback rules into distinct sentences would cost nothing and improve scanability.

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?

There is no output schema, so the description carries the return-value burden itself — and it does, naming each returned field and the enum-like payment statuses. For a 3-parameter read tool with an auth fallback, nothing an agent needs in order to call it correctly or interpret the result is missing.

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 coverage is 100%, so baseline is 3. The description adds modest value on top: it states `bookingId` is required and comes from `list_bookings`, and it explains the consequence of `email` (magic link, `magicLinkSent: true`) more concretely than the schema wording. The `sessionToken` parameter is left unaddressed in the description, which keeps it from a 5.

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?

Opens with a specific verb+resource ("Returns the full details of one existing booking") and enumerates the returned fields: hotel, dates, rooms, guests, contact person, total price, payment status, cancellation policy. It is clearly separable from siblings: `list_bookings` is named as the source of the ID, `cancel_booking` is named as the mutation counterpart, and the credit-line statement endpoint is distinguished from the `CREDIT_LINE` status value.

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?

Gives explicit when-to-use: read fee/refund terms BEFORE cancelling, with the reason stated ("`cancel_booking` itself does not return a fee preview"). Also covers the precondition branch (signed-in session required, guest sessions cannot view) and the fallback path (pass `email` when unauthenticated), so the agent knows both the trigger and the alternative.

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