Stream

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

With no annotations provided, the description carries the full burden. It discloses that voiding is irreversible ('can no longer be paid'), which is a key behavioral trait for a destructive operation. However, it doesn't mention other important aspects like permissions needed, error handling, or what the output contains, leaving gaps in behavioral context.

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 two concise sentences with zero waste: the first states the action and resource, and the second explains the consequence. It's front-loaded with the core purpose and efficiently structured, earning its place fully.

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 tool's complexity (destructive operation with no annotations) and the presence of an output schema (which handles return values), the description is reasonably complete. It covers the irreversible nature but could improve by mentioning prerequisites like invoice status or linking to sibling tools for better context.

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 has 0% description coverage, so the description must compensate. It doesn't explicitly mention the 'invoice_id' parameter, but the context of 'an unpaid invoice' implies an identifier is needed. Since there's only one parameter, the description adequately conveys the semantics without detailed param info, meeting the baseline for 0 params.

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 clearly states the action ('void (cancel)') and resource ('an unpaid invoice'), making the purpose explicit. However, it doesn't differentiate from sibling tools like 'delete_customer' or 'refund_payment', which are also destructive operations, so it misses full sibling distinction.

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 usage by specifying 'unpaid invoice' as a prerequisite, but doesn't explicitly state when to use this tool versus alternatives like 'refund_payment' for paid invoices or 'delete_customer' for other cancellations. It provides some context but lacks clear exclusions or named alternatives.

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