Send an invoice by email outside the normal schedule, with test mode that emits the event without delivering anything.
Email an invoice to the customer outside the normal schedule. Test mode sends nothing but still emits the event.
| Name | Required | Description | Default |
|---|---|---|---|
| invoice | Yes | The ID of the invoice. |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only declare readOnlyHint=false and openWorldHint=true, so the description carries weight by disclosing a real behavioral trait: 'Test mode sends nothing but still emits the event.' That tells the agent about a side effect that survives even when no email goes out, which is not derivable from the annotations or schema.
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 sentences, zero filler, with the core action front-loaded ahead of the test-mode caveat. Every sentence earns its place.
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?
For a single-parameter mutation tool with no output schema, the description covers the action and a key behavioral caveat. It leaves out error conditions (e.g., sending an already-paid or draft invoice) and required permissions, but the annotations cover the safety profile.
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?
There is only one parameter and the schema already documents it at 100% coverage ('The ID of the invoice.'). The description adds no format, ID prefix, or constraint detail beyond the schema, so the baseline 3 is correct.
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?
States a specific verb and resource: 'Email an invoice to the customer.' An agent can distinguish this from stripe_invoices_create and stripe_invoices_list without opening any schema. It stops short of naming a sibling alternative, so it lands at a clear-but-undifferentiated 4.
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?
'Outside the normal schedule' implies when this tool is preferred over the automatic sending behavior, which is useful implied context. However, there is no explicit when-not guidance, no mention of prerequisites like invoice finalization, and no named alternative among siblings.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.