erp-mcp

post_vendor_invoice

Idempotent

Validates and posts vendor invoices, with preview-only checks by default and idempotent confirmed creation to prevent duplicate ERP documents.

Instructions

Post a vendor invoice. Without confirm it only runs the checks and returns a preview.

Posting is idempotent: repeating a confirmed call with the same vendor and reference returns the document that was already created.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "vendor_tax_id": "<vendor_tax_id>",
      "reference": "<reference>",
      "document_date": "<document_date>",
      "gross_amount": "<gross_amount>",
      "tax_amount": "<tax_amount>",
      "currency": "<currency>"
    },
    "name": "post_vendor_invoice"
  }
}

Input Schema

Name	Required	Description
`confirm`	No
`currency`	Yes
`reference`	Yes	Invoice number as printed
`tax_amount`	Yes
`gross_amount`	Yes
`document_date`	Yes
`vendor_tax_id`	Yes	Tax number printed on the invoice
`purchase_order`	No

Output Schema

Name	Required	Description	Default
`checks`	Yes
`posted`	Yes
`next_step`	Yes
`document_number`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Nov 12, 2026

TDQS

B3.4/5.0

Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, and the description earns credit for explaining the dry-run semantics of 'confirm' and for defining the idempotency key (same vendor and reference). However it says nothing about what happens on validation failure, whether a rejected preview throws or returns errors, or what permissions posting requires.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight paragraphs with the primary action and the safety-relevant preview mode front-loaded; nothing is redundant. Minor awkwardness in splitting the idempotency sentence mid-paragraph, but no wasted wording.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists, so return values need not be described, and the critical mutation semantics (preview vs commit, idempotency) are covered. For a six-required-parameter write tool with only 25% schema coverage, though, guidance on amount/currency formats and PO optionality is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 25% and five parameters (currency, gross_amount, tax_amount, document_date, purchase_order) carry no documentation in either the schema or the description. The description does add real meaning for 'confirm' (dry-run switch) and 'reference' (idempotency key), but it never explains that amounts accept string or numeric forms, the ISO-4217 currency pattern, or that purchase_order is optional.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb+resource ('Post a vendor invoice'), so the action is unambiguous. Sibling tools operate on different resources (purchase orders, vendors), so no explicit differentiation is needed, though it never states what an invoice posting produces beyond 'the document'.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly explains the two modes: without 'confirm' the call only runs checks and returns a preview, implicitly telling the agent to use preview-then-confirm. It does not state prerequisites such as vendor existence or PO validity requirements, and names no alternative tool.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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