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

The annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the danger profile is structured. The description usefully adds a consent requirement and a timing window, but says nothing about what cancellation does to the order afterwards (irreversibility, refund, notification) and no output schema exists to cover the result.

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 timing constraint before the parameter and consent notes. 'Before making starts' relies on unexplained domain jargon ('making') that could be sharper, but no sentence is wasted.

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 destructive, non-read-only mutation with no output schema, an agent still lacks the post-call picture: what is returned, whether the cancellation is reversible, and how a phone-mismatch failure surfaces. The core call requirements are covered, so it is adequate rather than 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 0% and both parameters are plain untyped strings, so the description carries the burden. It clarifies that phone is 'the phone number it was placed with' — i.e. a verification match — which is genuine added meaning, but it gives no format or normalization guidance (country code, digits only) and doesn't say what happens if the phone mismatches.

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 ('Cancel an order') plus a timing scope ('before making starts'), which separates it from confirm_order, place_order and track_order. It doesn't name a sibling explicitly, so the differentiation is implicit rather than stated.

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?

'Only do this if the person asks' is an explicit consent gate, and 'before making starts' gives a clear precondition window. It stops short of naming alternatives (e.g. modifying rather than cancelling), but the when-to-use condition is unambiguous.

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