update_purchase_invoiceUpdate draft purchase invoice fields by ID. Server-managed fields are rejected, and confirmed invoice dates must be invalidated first before changes.
Update draft purchase-invoice fields. Server-managed fields are rejected; confirmed invoice dates require invalidate_purchase_invoice first.
| Name | Required | Description | Default |
|---|---|---|---|
| id | Yes | Invoice ID | |
| data | Yes | Object with fields to update. |
Changes observed during successful MCP inspections.
v0.29.2Input schema / additionalPropertiesAdded value: +falsev0.18.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations cover the safety profile (not read-only, idempotent, non-destructive), and the description adds value beyond them by disclosing validation behavior (server-managed fields are rejected) and the invalidation prerequisite for confirmed dates. It does not disclose what a successful update returns or partial-failure behavior, but the additions are substantive.
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 tight sentences with zero filler, and the scope constraint and prerequisite are both front-loaded in the order an agent needs them.
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 2-parameter mutation with annotations present and no output schema, the description covers scope, the key validation rule, and the prerequisite. The main gap is that the allowed update fields for the opaque 'data' object are never illustrated or bounded.
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 coverage is 100% for the two parameters, so baseline is 3. The 'data' parameter is a free-form object with no field enumeration, and the description only vaguely implies which fields are updatable (draft fields, not server-managed ones) without listing or constraining them, so it adds only marginal meaning.
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 gives a specific verb+resource ('Update draft purchase-invoice fields') and constrains scope to drafts, which cleanly separates it from confirm/invalidate siblings. It stops short of full sibling differentiation since it does not contrast with adjacent tools like confirm_purchase_invoice or delete_purchase_invoice.
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?
It states a real precondition: confirmed invoice dates require invalidate_purchase_invoice first, naming the alternative explicitly. It also implies the operation is restricted to drafts, but gives no broader when-to-use/when-not-to-use framing beyond that one case.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.