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

Goes well beyond the annotations by enumerating side effects: delivery created, order_line.qty_shipped increased, item.on_hand decreased via core, order.status -> shipped when nothing remains. It also discloses the stock constraint ('cannot go negative') and the invariant that the order stays open for the shortfall — exactly the mutation context annotations like destructiveHint=false 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 purpose, then behavior, then effects — a good structure. The short-ship paragraph is slightly redundant, restating the 'don't silently reduce quantity' point twice, but every section still carries actionable content.

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?

No output schema exists, yet the description covers the mutation effects, the partial-shipment edge case, and the insufficient-stock failure mode. An agent has everything needed to invoke this correctly and report results.

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, but the description adds genuine meaning about the `lines` parameter's omission semantics (empty = ship all open, present = partial) and reinforces the open-quantity ceiling on qty. Carrier and tracking are only covered by 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?

States a specific verb and resource ('Record a shipment against a confirmed order') plus the precondition (order must be confirmed). The partial-shipment framing lets an agent distinguish this from o2c_close_short and o2c_invoice_shipped without opening another schema.

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 clear operating guidance: omit lines to ship everything open, pass lines for a partial ship, and ship available stock rather than silently reducing the ordered quantity. It does not name sibling tools (close_short, invoice_shipped, cancel_order) as explicit alternatives for the remaining cases, which keeps it below a 5.

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