MCP Email Server

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forward_email

Forward an email to new recipients, including the original content and attachments. Source is read via IMAP first; if unreadable, it is not sent, and per-recipient status is reported.

Instructions

Forward an existing message to new recipients using the specified account. The source message is read over IMAP first: if it cannot be read, the call fails before any SMTP session is opened, so a forward is never delivered without the content it was supposed to carry. The subject is derived from the source as 'Fwd: ' without stacking a second prefix, the caller's note is placed above a plain-text forwarded block re-composed from the source's parsed text body, and the source's attachments are re-attached with their original MIME types unless include_attachments is false. Partial or ambiguous SMTP delivery reports per-recipient succeeded/failed/unknown status and reports the independent Sent-copy outcome separately; ambiguous effects are not retried automatically. The response names the delivered message's RFC Message-Id once the provider accepts the message data, and reports no identifier for an ambiguous delivery.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`cc`	No	A list of CC email addresses.
`bcc`	No	A list of BCC email addresses.
`body`	No	An optional note placed above the forwarded content.
`email_id`	Yes	UID of the source message to forward.
`recipients`	Yes	A list of addresses that receive the forwarded message.
`account_name`	Yes	The name of the email account to forward from.
`source_mailbox`	No	The mailbox that contains the source message.	INBOX
`include_attachments`	No	Whether to re-attach the source message's attachments.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Addedv1.5.2Aug 28, 2026

TDQS

A4.7/5.0

Behavior5/5

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

The description richly discloses behavior beyond the annotations: IMAP-read-first failure mode, single 'Fwd:' prefix, body placement, attachment MIME preservation, per-recipient delivery statuses, sent-copy handling, no automatic retry, and Message-Id reporting. This goes well beyond the mutation hints in the annotations.

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 detailed but every sentence carries operational value: first sentence states purpose, then failure behavior, message composition, delivery reporting, and response semantics. There is no filler or repetition of schema information.

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?

Given the complexity of forwarding, the description covers failure conditions, attachment handling, subject derivation, ambiguous delivery outcomes, and identifier reporting. An output schema exists, so explicit return-value enumeration is not required; the description is complete enough for correct tool invocation and expectation-setting.

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 coverage is 100%, so the baseline is 3, but the description adds meaningful parameter context: body is placed above the forwarded block, include_attachments preserves original MIME types, and source_mailbox relates to the IMAP source read. Not every parameter receives added detail, but the added semantics exceed the baseline.

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 uses a specific verb, 'Forward', with a clear resource, 'an existing message', and target, 'new recipients using the specified account'. It is immediately distinguishable from sending a fresh message or listing/reading email operations among the siblings.

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 forwarding semantics are clear: use this when an existing message must be re-sent with its content and optionally its attachments. It does not explicitly name alternatives or exclusion cases, but the context strongly separates it from send_email and other sibling tools.

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

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