Mailbox MCP

Send an email

send_email

Destructive

Send a new email from the connected mailbox, with files attached if you pass them. This delivers real mail to real people and cannot be undone.

Input Schema

TableJSON Schema

Name	Required	Description
`cc`	No
`to`	Yes	Recipient email addresses.
`from`	No	Send as one of the other addresses on this mailbox instead of its default. Use it only when the user names an address to send from. It must be one already added to the mailbox; anything else is refused with the list of addresses that would have worked. The mail server still decides whether it will carry the address, and may refuse it at send time.
`html`	No	Optional HTML body. Send real markup, used exactly as given and never escaped or unescaped by us: `<p>Hi</p>`, never `<p>Hi</p>`. Escaped markup is delivered as visible tags and nothing will warn you. Leave it out unless you have real markup to send: the message still goes out as HTML, built from `text`, carrying the mailbox owner's HTML signature.
`text`	Yes	Plain text body.
`subject`	Yes
`attachments`	No	Files to attach. FOUR WAYS IN, AND ONLY ONE OF THEM COSTS YOU ANYTHING. For a file already in this mailbox, call read_email on the message holding it and pass the `ref` from its `attachments` list as `fileRef`. For a file on the web, pass its https:// link as `url` and this server fetches it. For a file on the person's own computer, make a link with create_upload_link and pass its `uploadId` once the file is up - one entry attaches everything that arrived there. Those three work at any size, because the bytes never pass through this conversation. `content` is the last resort and is only for something you generated yourself in this conversation that exists nowhere else: it costs roughly 450,000 tokens per megabyte, so keep it under about 50 KB. All attachments TOGETHER must come to under 10 MB - a whole-message limit, not an allowance per file, so three 4 MB files are refused however they arrived.
`plainTextOnly`	No	Send with no HTML part at all. Leave this out unless the user has asked for plain text or the recipient is a list that rejects HTML - it drops the mailbox owner's HTML signature and their formatting. Do not set it to be cautious; HTML is the normal format and what their own mail client sends.
`requestReadReceipt`	No	Ask the recipient's mail program to confirm when the message is opened, exactly as Outlook's "request a read receipt" tick box does. Only set it when the user asks for it. TELL THEM WHAT IT REALLY DOES before promising anything: it is a request their mail program may ignore and that many clients ask them to approve, so most messages never produce one however promptly they are read - consumer Gmail never sends one, Workspace only if an administrator enabled it, Apple Mail only behind a setting that ships off. Use check_receipts afterwards to see whether one came back, and never treat silence there as evidence the message was unread. There is no delivery-receipt option: that needs an SMTP feature none of the mail providers this connects to offer.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

First observedSep 5, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already mark the tool as destructive, but the description adds valuable real-world context: this sends real email to real people and cannot be undone. That goes beyond the bare destructiveHint and helps the agent weigh confirmation and user intent before invoking.

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?

Two tight sentences front-load the core action and the most important consequence. No filler or repetition, and every clause earns its place.

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 an irreversible, high-stakes send action, the description gives the essential warning and the schema provides deep detail on attachments, HTML handling, read receipts, and sending constraints. The main missing piece is any mention of the return value or how to follow up on a sent message, but the rich schema largely compensates.

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 about 78%, so the input schema already documents most parameters thoroughly. The top-level description only adds a generic mention of attachments and does not meaningfully explain parameters beyond what the schema provides, making 3 the appropriate 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 states a specific action ('Send a new email'), the resource ('from the connected mailbox'), and the key consequence ('delivers real mail to real people and cannot be undone'). The word 'new' distinguishes it from reply/forward tools, and 'real mail' separates it from draft_email.

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

Usage Guidelines3/5

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

The description implies this is the tool for actually sending mail rather than drafting, and the irreversibility warns the agent to be careful. However, it never explicitly says when to prefer draft_email or how this differs from reply_email/forward_email, so the guidance is mostly inferred rather than stated.

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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TDQS

A4/5.0

Disambiguation4/5

Most tools target clearly distinct actions, but there are several close pairs that require careful reading: check_bounces vs check_receipts, list_emails vs search_emails, and the send/reply/forward vs draft_email/draft_reply/draft_forward families. The descriptions are strong enough that a careful agent can disambiguate, but the boundaries are not always obvious from the tool names alone.

Naming Consistency5/5

Every tool uses a consistent snake_case verb_noun convention, such as check_bounces, list_mailboxes, send_email, and update_draft. Related operations use parallel forms like mark_read/mark_unread and flag_email/unflag_email, making the naming predictable and coherent.

Tool Count2/5

With 28 tools, this exceeds the 25+ threshold where a tool set starts to feel too heavy. Email is a broad domain and many tools are individually justified, but the surface could be consolidated, especially the draft_forward/draft_reply/draft_email and send_email/reply_email/forward_email variants.

Completeness4/5

The core email lifecycle is thoroughly covered: send, read, search, move, delete, drafts, replies, forwards, folders, flags, attachments, upload links, contacts, identities, deliverability, bounces, and receipts. The main gap is that permanent deletion is referenced as a separate operation but no such tool is actually provided, and contact/identity management is effectively read-only.

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