Fastmail MCP Server

move_email

Move an email to a different mailbox or folder by providing the email ID and the destination mailbox ID.

Instructions

Move an email to a different mailbox (folder). Use list_mailboxes to find mailbox IDs.

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": {
      "emailId": "<emailId>",
      "mailboxId": "<mailboxId>"
    },
    "name": "move_email"
  }
}

Input Schema

Name	Required	Description	Default
`emailId`	Yes	The email ID to move
`mailboxId`	Yes	The destination mailbox ID

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.3.0Aug 2, 2026

TDQS

A4.2/5.0

Behavior3/5

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

With no annotations provided, the description must convey behavioral traits. 'Move' implies a mutating action, but the description does not disclose potential side effects, required permissions, or return value. It is straightforward but minimal, adding little beyond the verb itself.

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?

The description is two short sentences. The first sentence states the core action, and the second provides a necessary usage detail. Every word earns its place, with 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?

For a simple two-parameter action with no output schema, the description gives enough information to invoke the tool correctly: it states the purpose and provides a workflow tip for finding mailbox IDs. It does not mention return values, but that is acceptable given the absence of an output schema and the tool's straightforward nature.

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?

The schema already describes both parameters with 100% coverage. The description adds a valuable tip: 'Use list_mailboxes to find mailbox IDs,' which helps the agent understand how to populate the mailboxId parameter correctly. This goes beyond the schema's basic descriptions.

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 tool's function: 'Move an email to a different mailbox (folder).' This uses a specific verb and resource, distinguishing it from sibling tools like delete_email or archive_email. The parenthetical '(folder)' adds helpful clarity.

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 provides a direct usage instruction: 'Use list_mailboxes to find mailbox IDs.' This tells the agent a necessary prerequisite step for obtaining the destination mailbox ID. It does not explicitly mention alternatives or exclusions, but the guidance is clear and practical.

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