TrueNAS MCP

Truenas Call

truenas_call

Directly call TrueNAS middleware API methods by name with optional positional parameters to query and manage pools, users, services, alerts, and other resources.

Instructions

Call any TrueNAS middleware endpoint directly.

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": {
      "method": "<method>"
    },
    "name": "truenas_call"
  }
}

Input Schema

Name	Required	Description	Default
`method`	Yes	Middleware method name, e.g. "pool.query", "user.query", "service.query", "alert.list".
`params`	No	JSON array of positional arguments passed to the method. Most .query methods take [[filters]], e.g. [[["name","=","tank"]]].

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Oct 23, 2026

TDQS

C2.6/5.0

Behavior2/5

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

No annotations are provided, so the description carries the full burden, yet it says nothing about the fact that arbitrary methods may mutate or destroy state, that method names must be valid TrueNAS middleware names, or how errors surface. 'Directly' is the only hint that this bypasses the safety of typed endpoints.

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. It is efficient, though arguably efficient to a fault given how much an untyped passthrough needs to explain.

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?

An output schema exists so return values need not be described, but for an unannotated, arbitrary-method escape hatch the definition omits the essentials: that it can perform destructive writes, that it is a fallback to the typed siblings, and what happens with invalid method names.

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% and the schema itself explains the method name format and the [[filters]] convention for params, so the description adds nothing but also loses nothing. Baseline 3 applies when structured fields do all the work.

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

Purpose3/5

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

The description names a specific verb and resource ('call ... middleware endpoint') and the word 'directly' hints at raw passthrough rather than a typed operation. However, it never distinguishes this generic escape hatch from the 25+ dedicated siblings (list_pools, create_dataset, etc.), so an agent cannot tell from the description alone whether this is preferred or a fallback.

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?

There is no statement of when to use this versus the many specific sibling tools, nor any warning about when not to use it. The natural rule — 'use only when no dedicated tool covers the operation' — is left entirely to inference.

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