mcp-n8n-voice-orchestrator

dispatch_idempotent_n8n_workflow

Dispatch deterministic, idempotent webhook payloads to self-hosted n8n workflows; use unique keys to prevent race conditions from Vapi, Twilio, or WhatsApp.

Instructions

Dispatches a deterministic, lock-verified webhook payload to a self-hosted n8n workflow from Vapi, Twilio, or WhatsApp Cloud API.

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": {
      "workflowId": "<workflowId>",
      "idempotencyKey": "<idempotencyKey>",
      "channel": "<channel>",
      "payload": "<payload>"
    },
    "name": "dispatch_idempotent_n8n_workflow"
  }
}

Input Schema

Name	Required	Description
`channel`	Yes
`payload`	Yes	Structured lead or session state payload
`workflowId`	Yes	Target n8n webhook path or deterministic workflow ID
`idempotencyKey`	Yes	Unique call_id or message_id to prevent race conditions

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.2.0Nov 12, 2026

TDQS

C2.9/5.0

Behavior2/5

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

With no annotations, the description carries the full behavioral burden. The phrases "deterministic, lock-verified" hint at idempotency and locking, but the description never says what actually happens on a duplicate key (dedupe, cached response, or error), whether the dispatch is synchronous or fire-and-forget, what auth the self-hosted endpoint requires, or what side effects occur downstream in n8n.

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?

A single front-loaded sentence with no filler; the core action and target come first. It is dense to the point of jargon ("deterministic, lock-verified") without unpacking those terms, which costs a point but not efficiency.

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

Completeness2/5

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

This is a four-required-parameter mutation/dispatch tool with a nested free-form payload object, no annotations, and no output schema. The description says nothing about expected payload fields, return values, failure modes, or idempotency semantics — substantial gaps for a tool of this complexity.

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?

Schema coverage is 75%, so the schema already documents workflowId, idempotencyKey, and payload. The description's channel list (Vapi, Twilio, WhatsApp Cloud API) merely restates the enum values rather than adding meaning. It contributes nothing about payload shape or idempotency key format beyond what the schema says.

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 uses a specific verb ("Dispatches") and names the exact resource: a webhook payload delivered to a self-hosted n8n workflow, scoped to three named source channels. It is unambiguous about what the tool does. There are no sibling tools, so no differentiation is needed or possible.

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?

It never states when to use this tool versus any alternative, nor when not to use it. There is no guidance on retry behavior, on whether repeat calls with the same idempotencyKey are safe or expected, or on prerequisites such as a configured webhook target — the agent must infer all of this.

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

Deploy Server

Other Tools

dispatch_idempotent_n8n_workflowC