Email an invoice to its customer by providing the invoice ID. Automatically resolves sender and customer email, with optional subject and body customization.
Email an invoice to its customer. Looks up the sender address and the customer's email automatically.
| Name | Required | Description | Default |
|---|---|---|---|
| body | No | ||
| subject | No | ||
| invoiceId | Yes |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description adds useful behavior beyond the annotations by disclosing that sender address and customer email are resolved automatically. But it does not mention consequences of sending, such as whether the invoice is marked as sent or whether repeated sends are possible, despite idempotentHint being false and no readOnlyHint.
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?
Two short, information-dense sentences. The first delivers the core action, and the second adds the key lookup behavior with no filler or redundant wording.
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?
This is a side-effecting external communication tool with no output schema and minimal annotations, yet the description does not explain success/failure behavior, what happens after sending, or error cases like a missing customer email. It is enough to select the tool but not to invoke it confidently in all realistic situations.
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?
Schema description coverage is 0%, so the description must compensate, but it does not explain the optional body and subject parameters or their defaults. It only implicitly clarifies that invoiceId identifies the invoice and that recipient addresses are auto-resolved.
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 states a specific action and resource: 'Email an invoice to its customer.' This clearly distinguishes it from sibling tools like send_estimate and update_invoice, and the added detail about automatic address lookup sharpens what the tool uniquely does.
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 makes it clear this tool is for emailing invoices, which implies the appropriate context. However, it does not explicitly state when not to use it or mention alternatives such as send_estimate, nor does it note preconditions like the invoice being finalized or the customer having a valid email.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.