proton-mail-mcp

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create_folder

Idempotent

Create a new mailbox folder under the 'Folders/' namespace. Handles existing folders gracefully and provides clear error guidance for invalid paths.

Instructions

Create a new mailbox folder. Returns gracefully if the folder already exists. On Proton Mail, folders must be created under the "Folders/" namespace (e.g. "Folders/Receipts") — root-level paths are rejected by the server with an actionable error.

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": {
      "path": "<path>"
    },
    "name": "create_folder"
  }
}

Input Schema

Name	Required	Description	Default
`path`	Yes	Folder path to create. On Proton, prefix with 'Folders/' (e.g. 'Folders/Receipts', 'Folders/Newsletters/Politics').

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.1May 30, 2026

TDQS

A4.4/5.0

Behavior5/5

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

Beyond annotations (idempotentHint=true), the description reveals that the tool gracefully handles existing folders and that root-level paths trigger an actionable error. This adds valuable behavioral context.

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?

Three sentences, each adding unique value: purpose, idempotency, and a usage constraint. No redundancy or unnecessary detail.

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 adequately covers what the tool does, its idempotent behavior, and a key failure scenario. It does not describe the return format, but for a tool without an output schema, the information provided is sufficient for correct usage.

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 schema already describes the 'path' parameter in detail with examples. The description reiterates the prefix requirement but adds no new semantic information about the parameter itself, so baseline 3 applies.

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 description clearly states the action 'Create a new mailbox folder' and distinguishes it from sibling tools like 'create_label' by specifying it creates folders. The Proton-specific namespace requirement provides additional precision.

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?

The description implies when to use this tool (to create a folder) and provides important usage constraints (Proton 'Folders/' prefix, idempotent behavior). However, it does not explicitly contrast with alternative tools like 'rename_folder' or 'delete_folder'.

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