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

Even though annotations already flag destructiveHint and non-idempotent, the description adds value beyond them: it warns the action cannot be undone, describes the state precondition and error behavior, and explains the internal ETag/If-Match read before the POST. This is exactly the operational context annotations can't 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?

Three tight sentences, front-loaded with the WRITE classification and fully earning their place: scope, irreversibility/precondition, then mechanics. No filler.

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 mutation with no output schema, the description covers reversibility, precondition, error behavior, and the ETag handshake. An agent has everything needed to attempt the call and interpret failure.

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 all three parameters (order_id, reason, charge) are already documented in the schema. The description restates them (transaction id, reason, optional fee) but adds little syntax or semantics beyond the schema. 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?

The description opens with a specific verb and resource ('WRITE: cancel one order by transaction id') and names the exact required inputs, so an agent can immediately distinguish it from extensiv_get_order or extensiv_list_orders. The scope is unambiguous.

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?

It clearly states the precondition (the order must be in a state the warehouse can still cancel, otherwise Extensiv errors) and that the tool first reads the order for its ETag. It doesn't name a sibling alternative, but for a terminal cancel action there is plausibly none.

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