send_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 does mention a reversibility trait ('Can be voided and re-sent'), which adds some transparency. However, it fails to disclose important side effects such as whether the invoice status changes, whether an email is actually sent immediately, permission requirements, or error behavior—critical gaps for a mutation tool with no annotation support.

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 exactly two sentences, with the first sentence stating the core purpose and the second adding a key behavioral trait. There is no redundant text or filler, and the information is front-loaded. This is appropriately sized and well-structured.

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?

The tool is simple (one required parameter), and the description covers the basic action and a notable reversibility feature. However, with no output schema and no annotations, the description should have explained what happens after sending (e.g., return value, success/failure indications) and any constraints on invoice state. The note about voidability helps but is not enough to make the tool fully self-explanatory.

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 description adds no information about the parameters. The schema documents 'email' as an override but leaves 'invoiceId' entirely unspecified; with schema description coverage at 50%, the description should have compensated for the missing parameter explanation. The tool name implies invoiceId is the invoice to send, but the description does not clarify this or the relationship between email and invoiceId.

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 ('Email an invoice to the customer') with a specific verb and resource. It distinguishes itself from sibling tools (get_invoice, list_invoices, archive_customer, delete_account) which handle viewing, archiving, or deleting rather than sending. The additional note about being voidable and re-sent adds useful scope.

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 usage is implied through the purpose (use this when you need to email an invoice), but there is no explicit guidance on when to use this tool versus alternatives, nor any exclusions or prerequisites. Sibling tools are listed but not referenced in the description, so the agent must infer the appropriate context.

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