Cancel transaction

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

Adds context beyond annotations: 'possibly irreversible', 'legally-binding signature request and/or quota consumption', and 'This cannot be undone'. Annotations already indicate destructiveHint true, so description enhances understanding.

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?

Very concise: two sentences plus a warning emoji. Front-loaded with critical warning, no unnecessary words.

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?

Given simple single-param tool with annotations and no output schema, description covers essential behavioral traits and usage guidance. Could mention expected outcome or return, but overall adequate.

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?

Only one parameter, transactionId, with schema description 'The transaction ID (txn_…).' Description adds no additional meaning beyond schema. Schema coverage is 100%, so 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?

Description clearly states the tool cancels a 'low-level transaction', which distinguishes from sibling 'cancel_signing_session'. However, it doesn't explicitly list alternatives or when to prefer this over other cancellation tools.

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?

Includes a prominent warning that the action is consequential, possibly irreversible, and advises confirming with the human before calling. Does not mention specific situations when not to use or alternatives.

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