mcp-proton-mail

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Save a forwarding draft

forward_message

Save an unsent draft that forwards a message with only chosen attachments; it never sends. Use it to forward mail with selected attachments and optional note above the forwarded text.

Instructions

Save an unsent draft that forwards one message with only the attachments you choose; this never sends.

Use it to forward mail; use compose_reply or create_draft to reply or write new mail. Pick attachments by their list_attachments indexes: the argument is required, and [] forwards none. note goes above the forwarded text. It needs no preview.

The draft has the original's headers and text under a Fwd: subject. A longer original is cut at read_thread's text limit, marked in the draft and in warnings. Limits as for create_draft: 20 files, 7 MiB of them, and the 10 MiB send limit.

Returns draft_id, subject, attachments, not_forwarded, size_note, warnings and next_steps. Refuses an unknown message, an index it does not have, or a From address list_from_addresses does not allow.

Input Schema

Name	Required	Description
`cc`	No	An address, or a list of addresses.
`to`	Yes	An address such as a@example.test, or a list of addresses.
`note`	No	Text to put above the forwarded message.
`message_id`	Yes	The message's RFC Message-ID, as search_mail returns it, such as <a@example.test>. Not an IMAP UID.
`attachments`	Yes	Indexes from list_attachments to forward. Required, even when empty: [] forwards none.
`from_address`	No	Use this From address instead of the default: one that list_from_addresses allows, exactly as listed.

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 2, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations declare non-read-only, non-destructive, non-idempotent, but the description adds the crucial fact that nothing is sent, how the original is reproduced ('headers and text under a Fwd: subject'), truncation at read_thread's limit with warnings, and concrete limits (20 files, 7 MiB, 10 MiB). It also names refusal conditions (unknown message, missing index, disallowed From). Minor gap: it does not say whether re-running with the same inputs creates a duplicate draft despite idempotentHint=false.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with the core action and a hard safety fact, then usage routing, then limits and failure modes. It is on the long side, and the return-field enumeration repeats what the output schema already declares, but there is no filler.

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?

For a six-parameter draft-creation tool with an output schema, the description covers the safety profile, attachment selection, truncation behavior, size limits, refusal cases, and next_steps. An agent has everything needed to call it correctly and interpret the result.

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 coverage is 100% and the description largely restates it: the attachments index/`[]` semantics and the meaning of note are already in the schema property descriptions. The one added nuance is the consequence of a bad index (rejection) and the interaction with list_from_addresses for from_address, but there is no format or syntax detail beyond the 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?

Opens with a specific verb+resource+scope: 'Save an unsent draft that forwards one message with only the attachments you choose; this never sends.' It immediately distinguishes the operation from writing or replying, so an agent can tell it apart from create_draft and compose_reply without opening either schema.

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 routes among siblings: 'Use it to forward mail; use compose_reply or create_draft to reply or write new mail.' It also explains how to obtain the attachments argument and that no preview step is needed, covering both the when and the how.

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