mail-mcp

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graph_send_message

Send email via Microsoft Graph API (required for personal hotmail/outlook.com accounts where SMTP is blocked). Before calling, show the user a full preview (To, CC, BCC, subject, rendered body, attachments) and get explicit confirmation.

Instructions

Input Schema

Name	Required	Description	Default
`cc`	No	CC recipients (optional, max 50)
`to`	Yes	Recipient email addresses (1..50)
`bcc`	No	BCC recipients (optional, max 50)
`subject`	Yes	Email subject (1..998 characters)
`reply_to`	No	Reply-To address (optional)
`body_html`	No	HTML body (at least one of body_text or body_html required). Separate field from `body_text`: pass the HTML itself, never wrapped in pseudo-tags like `<body_html>`; the server rejects them.
`body_text`	No	Plain text body (at least one of body_text or body_html required). Separate field from `body_html`: never concatenate the two or wrap content in pseudo-tags like `<body_text>`; the server rejects them.
`account_id`	No	Account identifier (defaults to `"default"`)	default
`references`	No	References header for threading (optional)
`attachments`	No	File attachments (optional, base64-encoded)
`in_reply_to`	No	In-Reply-To message ID for threading (optional)
`save_to_sent`	No	Save to Sent Items folder (default: true)

Output Schema

Name	Required	Description
`data`	Yes	Tool-specific data payload
`meta`	Yes	Execution metadata (timestamp, duration)
`summary`	Yes	Human-readable summary of the operation outcome

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedv0.6.0Oct 22, 2026

changedInput schema / properties / body_html / description

Previous value: -"HTML body (at least one of body_text or body_html required)"New value: +"HTML body (at least one of body_text or body_html required).\nSeparate field from `body_text`: pass the HTML itself, never wrapped\nin pseudo-tags like `<body_html>`; the server rejects them."

changedInput schema / properties / body_text / description

Previous value: -"Plain text body (at least one of body_text or body_html required)"New value: +"Plain text body (at least one of body_text or body_html required).\nSeparate field from `body_html`: never concatenate the two or wrap\ncontent in pseudo-tags like `<body_text>`; the server rejects them."

First observedv0.4.12Sep 9, 2026

TDQS

A4/5.0

Behavior4/5

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

With no annotations, the description carries the burden and does add genuine behavioral value: it discloses that the send is user-visible and irreversible enough to require a full rendered preview and explicit confirmation. Credential requirements (OAuth2 Mail.Send) and the POST /me/sendMail mechanism live in the schema description rather than here, and nothing is said about failure or rate-limit behavior.

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 sentences, both load-bearing: the first establishes what and why/how it differs, the second establishes the mandatory confirmation gate. Nothing to trim and the routing fact is front-loaded.

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?

An output schema exists and all 12 parameters are documented, so the description need only cover selection and workflow, which it does. The one gap is not mentioning the sibling send tools by name for the non-personal-account case.

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%, including per-parameter notes on body_html vs body_text, attachment file_path vs content_base64, and recipient limits. The description adds no parameter-level information, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource (send email) plus the transport mechanism (Microsoft Graph API), which is the key axis distinguishing it from the SMTP/EWS send siblings. It does not name those siblings directly, so the differentiation is implied rather than explicit.

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?

Gives a clear selecting condition: required for personal hotmail/outlook.com accounts where SMTP is blocked. It also prescribes a pre-call workflow (full preview, explicit confirmation). It stops short of stating the inverse case (use smtp_send_message for accounts where SMTP works), leaving the agent to infer it.

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