Modify an existing invoice by ID, updating line items, dates, notes, template, or reference number.
Update fields on an existing invoice.
| Name | Required | Description | Default |
|---|---|---|---|
| items | No | ||
| notes | No | ||
| due_date | No | ||
| invoiceId | Yes | ||
| invoice_date | No | ||
| template_name | No | ||
| reference_number | No |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden and delivers almost none of it: it does not say whether this is a partial or full replacement, whether omitted fields are preserved, what permissions are needed, or whether the change is reversible. Only 'existing' hints at a failure mode for a missing invoice.
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?
It is a single front-loaded sentence with no filler, so it is not bloated. But at one generic clause for a 7-parameter mutation tool it is under-specified rather than genuinely concise.
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?
A mutation tool with 7 undocumented parameters, zero annotations, and no output schema needs the description to do substantial work, and this one provides essentially nothing about behavior, required inputs, or results.
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% across 7 parameters, and the description supplies no parameter meaning at all — not even that items replaces or appends to line items, or that invoiceId is required. The description leaves the agent entirely dependent on field names in the schema.
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 and resource ('Update fields on an existing invoice'), which clearly separates it from create_invoice and delete_invoice by name. It does not, however, add anything that distinguishes it from the parallel update_estimate / update_customer siblings beyond the resource noun.
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?
There is no guidance on when to use this tool versus create_invoice, send_invoice, or the get_* readers. 'Existing invoice' is the only implicit precondition and no exclusions or alternatives are named.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.