proton-mail-mcp

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create_label

Idempotent

Create a new Proton label to organize messages with non-exclusive tags. Labels can be applied to multiple messages alongside folders.

Instructions

Create a new Proton label. Pass the bare label name (e.g. "Important") — the tool prepends the "Labels/" namespace internally. Labels are non-exclusive tags: a message can carry many labels in addition to living in one folder. Apply or remove labels on messages with update_message_labels. Idempotent — succeeds silently if the label already exists.

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": {
      "name": "<name>"
    },
    "name": "create_label"
  }
}

Input Schema

Name	Required	Description	Default
`name`	Yes	Bare label name (e.g. "Important", "Work"). Do not include the "Labels/" prefix.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.1May 30, 2026

TDQS

A4.9/5.0

Behavior5/5

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

Annotations already indicate idempotentHint=true, but description adds critical behavioral details: automatic namespace prepending, non-exclusive nature of labels, and silent success on duplicates. No contradictions.

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, front-loaded with purpose, each sentence serves a distinct purpose (what, how, idempotency). No wasted words.

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

Completeness5/5

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

No output schema, but description fully explains behavior, including namespace handling, label semantics, and idempotency. Sufficient for an agent to use correctly.

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

Parameters4/5

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

Schema covers the single parameter 'name' with clear description. The description reinforces the bare name requirement and explains the internal transformation, adding value beyond schema.

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?

Clearly states 'Create a new Proton label' with specific verb and resource. Distinguishes from sibling tools like create_folder and update_message_labels by explaining labels are non-exclusive tags.

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

Usage Guidelines5/5

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

Explicitly instructs to pass bare label name without prefix, explains namespace prepending, labels' non-exclusivity, and directs to update_message_labels for applying/removing labels. Also notes idempotency for duplicate attempts.

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