Fastmail MCP Server

send_draft

Send a saved draft email by providing its ID. The draft must already exist in the Drafts mailbox; sender identity is auto-detected if not specified.

Instructions

Send a previously saved draft email. The draft must already exist in the Drafts mailbox.

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>"
    },
    "name": "send_draft"
  }
}

Input Schema

Name	Required	Description	Default
`emailId`	Yes	The ID of the draft email to send
`identityId`	No	Sender identity ID. Auto-detected from draft if omitted.

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.3.0Aug 2, 2026

TDQS

A3.7/5.0

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 of behavioral disclosure. It mentions the prerequisite but omits important behavioral traits: what happens to the draft after sending (e.g., removed from Drafts), error conditions, permission requirements, or potential side effects. For a mutating operation, this is a significant gap.

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 sentences, front-loaded with the action, and every word earns its place. It clearly states the action and the key constraint without any wasted words.

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

Completeness3/5

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

For a simple 2-parameter tool, the description covers the essential precondition. However, with no output schema and no annotations, the return value, error behavior, and post-send effects are left unspecified, leaving some ambiguity for the agent.

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 description coverage is 100% with useful descriptions for both emailId and identityId. The description adds no extra parameter semantics beyond restating the draft context, so the baseline of 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 states a specific verb ('Send') and resource ('previously saved draft email'), and differentiates from siblings like send_email and reply_email by emphasizing the draft context and the requirement that it exists in the Drafts mailbox. This is clear and unambiguous.

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 gives clear context: use this tool when a draft has already been saved and needs to be sent. It states the prerequisite ('must already exist in the Drafts mailbox') but does not explicitly name alternatives (e.g., use send_email for new messages), so it falls short of a 5.

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