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

Annotations already declare destructiveHint=true, so the destructive nature is not new information. The description still adds value beyond them by stating the concrete consequence ('the proposal is closed and cannot be reopened') and imposing a confirmation workflow before invocation, which an agent cannot derive from the hints alone.

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 selection condition, followed by the consequence and the confirmation instruction. No filler and every sentence changes how an agent would act.

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?

An output schema exists, so return values need no explanation, and the description covers trigger, irreversibility, and the confirmation requirement. It leaves a minor gap around failure behavior (e.g., what happens if the proposal is no longer pending) but is otherwise sufficient for correct invocation.

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?

With one parameter at 100% schema description coverage, the schema already documents proposal_id including its UUID format. The description only reinforces the 'pending' state constraint, adding marginal meaning beyond what the schema already conveys, so the baseline of 3 is appropriate.

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 names a specific verb and resource ('cancel a pending trade proposal they sent'), and the phrase 'they sent' scopes it to the sender's own proposal, which implicitly separates it from receiver-side siblings like decline_proposal or accept_proposal. It does not name any sibling explicitly, so full differentiation still requires reading the sibling list.

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 gives a clear trigger ('when the user wants to cancel a pending trade proposal they sent') and an explicit pre-action requirement ('Confirm with the user first'). It stops short of naming the alternatives (e.g., counter_proposal vs. withdraw_proposal) or stating when not to use it, so the routing guidance is clear but not exhaustive.

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