cancel_invoice

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the action and a condition ('unpaid') without mentioning side effects, reversibility, error conditions, or permissions. For a state-changing operation, this is a significant gap in transparency.

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?

The description is a single, front-loaded sentence with no filler words. It efficiently communicates the tool's purpose without unnecessary detail, making it appropriately concise.

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 the low complexity of the tool (2 fully described parameters, no output schema), the description is minimally sufficient to convey the core action. However, as a mutation tool with no annotations, it would benefit from additional context about what 'cancel' actually does (e.g., whether it fails on paid invoices, what happens afterward), which prevents a higher score.

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?

The input schema provides descriptions for both parameters (wallet_id and payment_hash), covering 100% of parameters. The description text adds no additional parameter-specific meaning, so it does not improve upon the schema's baseline coverage.

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 'Cancel an unpaid Lightning invoice' clearly identifies the action (cancel) and the resource (Lightning invoice), with a specific qualifier (unpaid) that distinguishes it from sibling tools like create_invoice, pay_invoice, or cancel_subscription. This is a specific verb+resource pairing.

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 implies the tool is for canceling an invoice that has not been paid, which gives a clear context. However, it does not explicitly state when to use it versus alternatives or mention any exclusions, so guidance is only implied rather than explicit.

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