Update an invoice's status, due date, user, or currency to keep billing records accurate and current.
Update invoice status or due date.
| Name | Required | Description | Default |
|---|---|---|---|
| due_at | No | New due date | |
| status | No | New status | |
| user_id | No | Updated user ID | |
| invoice_id | Yes | Invoice ID | |
| currency_code | No | Updated currency |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. 'Update' implies a mutation, but the description does not disclose side effects of status changes (for example, whether setting 'paid' triggers payment processing or credit changes), permission requirements, reversibility, or validation behavior. It adds only minimal context beyond the name.
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 wasted words. It is appropriately concise for a simple mutation tool. It stops short of 5 only because the extreme brevity leaves important scope and behavior unstated, though that is more a completeness issue than a structure issue.
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 mutation tool with no annotations, no output schema, and five parameters, of which only one is required. The description does not explain side effects, permissions, required invoice_id context, or the enum implications of setting status to 'paid' or 'cancelled'. Although parameter descriptions cover the schema, the behavioral context needed to call this tool safely is largely missing.
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 100%, so the schema already documents all five parameters, including the status enum. The description merely repeats two of the five fields ('status' and 'due date') without adding format, default, or interaction details. Baseline 3 is appropriate when the schema does the heavy lifting.
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 verb ('Update') and resource ('invoice'), and narrows scope to status or due date. It is clear enough to distinguish from get_invoice, list_invoices, create_invoice, and delete_invoice. It is not a 5 because the stated scope omits other editable fields present in the schema (user_id, currency_code), which can mislead about what the tool can update.
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 gives no guidance on when to use this tool versus alternatives such as get_invoice or list_invoices, nor does it mention prerequisites like needing an existing invoice. There are no explicit when-to-use or when-not-to-use statements. This matches the calibration level of narrow, unguided mutation descriptions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.