n8n-mcp

validate_workflow

Read-onlyIdempotent

Validate n8n workflows for structure, connections, expressions, and AI tools. Get errors, warnings, and fixes to ensure deploy-ready workflows.

Instructions

Full workflow validation: structure, connections, expressions, AI tools. Returns errors/warnings/fixes. Essential before deploy.

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": {
      "workflow": "<workflow>"
    },
    "name": "validate_workflow"
  }
}

Input Schema

Name	Required	Description	Default
`options`	No	Optional validation settings
`workflow`	Yes	The complete workflow JSON to validate. Must include nodes array and connections object.

Output Schema

Name	Required	Description	Default
`valid`	Yes
`errors`	No
`summary`	Yes
`warnings`	No
`suggestions`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.84.0Sep 11, 2026

TDQS

A4/5.0

Behavior3/5

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

Annotations already provide readOnlyHint and idempotentHint, so the safety profile is clear. The description adds that it returns errors/warnings/fixes, which is useful but not extensive. Since annotations carry the behavioral burden, the description adds moderate value.

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?

Two sentences, front-loaded with purpose and scope. Every word adds value. No redundancy or filler.

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

Completeness4/5

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

The description covers the tool's purpose and return type. An output schema exists, so return details are documented elsewhere. Slightly missing mention of the optional 'options' parameter, but the schema covers it. Overall adequate for a validation tool with rich structured data.

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 100% with detailed descriptions for each parameter. The description mentions the validation categories (structure, connections, expressions) which map to options, but does not add new meaning beyond what the schema already provides. Baseline 3 is appropriate.

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?

Clear verb+resource: 'Full workflow validation' specifies the action and scope. Lists what is validated (structure, connections, expressions, AI tools) and what is returned (errors/warnings/fixes). Distinguishes from sibling 'validate_node' by being for the entire workflow.

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?

States 'Essential before deploy' which implies when to use it, but does not explicitly mention when not to use it or alternatives like validate_node for single nodes. The context is clear but lacks exclusions.

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

Deploy Server