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

The description states 'Calling this changes nothing: it returns a preview of what would change,' which directly contradicts the destructiveHint=true and idempotentHint=false annotations (a no-op preview would be non-destructive and idempotent). An agent reconciling the schema annotations against the prose gets contradictory safety signals about whether calling this mutates state.

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?

Three short sentences, front-loaded with the action and then the crucial behavioral caveat. The money-units sentence is only loosely relevant to a tool whose sole parameter is an order number, so it is slightly off-target, but overall the text is tight.

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 single-parameter mutation tool with no output schema, the description covers what happens on call (preview plus confirmation link) and who can complete the action (the merchant). It leaves the preview contents somewhat unspecified but is broadly complete.

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% for the single orderNumber parameter, so the schema already documents it fully and the baseline is 3. The description adds no parameter-specific guidance; the 'Money is integer minor units (cents)' sentence does not apply to orderNumber, so it does not compensate or add param meaning here.

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 first sentence states a specific verb+resource ('Cancel an order'), so an agent immediately knows the operation and the target. It does not explicitly differentiate itself from closely related siblings such as orders_refund, orders_fulfil, or orders_mark_delivered, so it stops short of a 5.

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 useful workflow context (it is a preview step, only the merchant can finalize via the confirmation link), which implies when this tool is appropriate. However, it never explicitly states when to choose this over alternatives like orders_refund or when not to call it, leaving routing to inference.

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