fiken-mcp

fiken_update_invoice

Update an invoice's due date or mark it as manually sent using the Fiken API.

Instructions

Updates an invoice (due date and/or manual send status)

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": {
      "invoiceId": "<invoiceId>"
    },
    "name": "fiken_update_invoice"
  }
}

Input Schema

Name	Required	Description
`invoiceId`	Yes
`newDueDate`	No	New due date YYYY-MM-DD
`sentManually`	No	Mark invoice as manually sent

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.1.0Jul 30, 2026

TDQS

B3.3/5.0

Behavior2/5

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

The description only states the basic update action, adding no behavioral context beyond what the annotations (readOnlyHint: false) already imply. It does not disclose side effects, required permissions, reversibility, or any other traits that would help the agent anticipate the tool's behavior.

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

Conciseness5/5

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

The description is a single sentence of 9 words, conveying the essential information without any filler. It is front-loaded and efficient.

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?

For a simple update tool with only two optional fields and no output schema, the description covers the core purpose adequately. However, it lacks details on required authentication, idempotency, or potential error conditions, which would be helpful for a complete understanding.

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

Parameters3/5

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

The description adds context by naming the updatable fields (due date and manual send status), which maps to the two optional parameters. However, it does not clarify the meaning of invoiceId beyond the schema. With 67% schema coverage, the description partially compensates but could be more explicit.

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

Purpose5/5

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

The name and description clearly state the verb 'Updates' and the resource 'invoice', specifying the exact fields that can be updated (due date and/or manual send status). This effectively distinguishes it from sibling tools like fiken_create_invoice, fiken_get_invoice, and fiken_send_invoice.

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

Usage Guidelines2/5

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

The description fails to provide any guidance on when to use this tool versus alternatives, such as fiken_update_invoice_draft for drafts, or prerequisites like the invoice being in a certain state. No when-not-to-use or exclusion criteria are given.

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

Deploy Server