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

Goes well beyond the annotations by disclosing partial-failure semantics (a wholly-failed call when a tracking number is unknown, per-order success/error in each manifest), the carrier-billing consequence ('the carrier then collects and bills the parcels'), the irreversibility of booking, and the rule that an all-failed reply is itself an error. This is exactly the extra context destructiveHint=true and non-idempotency cannot convey.

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-loads the operation type and purpose in the first clause, then layers precondition, failure behavior, and irreversibility. Every sentence carries operational information; nothing is padded.

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?

With no output schema, the description still explains what comes back (one manifest per carrier, per-order success/error) and how to interpret an all-failed response. For a destructive, non-idempotent write tool, that covers everything an agent needs before invoking it.

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% and both parameters are documented there, including the confirm-must-be-true rule and the tracking-number format. The description's 'Requires confirm: true' largely restates the schema, and it adds no format or batching guidance beyond 'labelled orders', so the baseline 3 applies.

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?

States a specific verb and resource ('book labelled orders with their carriers for pickup') and names the exact step in Shippit's workflow ('the Shippit book step'). The 'WRITE:' prefix immediately separates it from read tools and from shippit_label_order, which is the preceding step.

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?

Clearly states the precondition ('Orders must have been labelled first (shippit_label_order)'), which routes the agent to the correct prior sibling. It also warns that 'booked orders can no longer be edited' and that confirm must be obtained from the user. It doesn't explicitly contrast with shippit_cancel_order or state when booking is inappropriate, so it falls short of the full 5.

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