m365-mcp

Reply to Email

email_reply

Send a reply to an email to just the sender or everyone, with optional attachments and CC recipients. Requires user approval via confirm=true before sending.

Instructions

Reply to an email, either to the sender only (mode='sender') or to everyone on it (mode='all'). Requires confirm=true after the user approves the reply. Returns the conversation the reply joined.

Input Schema

Name	Required	Description	Default
`cc`	No	Extra Cc recipients.
`body`	Yes	Reply text.
`mode`	Yes	sender: reply to the sender. all: reply all.
`confirm`	Yes	Must be true to send this reply; set only after the user approves.
`email_id`	Yes	Email to reply to.
`account_id`	No	Account ID or email address. Omit when only one account is signed in.
`attachments`	No	Local files to attach: at most 10, each at most 25 MB.
`body_format`	No	Format of the body text you supply.	text

Output Schema

Name	Required	Description
`mode`	Yes
`status`	Yes
`summary`	Yes	One-line human summary. The tool's text content is this result serialized as JSON (summary included), so a client that ignores structuredContent still sees every field.
`in_reply_to`	Yes
`conversation_id`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed22 schema fields changedv1.0.0Sep 29, 2026

addedInput schema / $schema

Added value: +"https://json-schema.org/draft/2020-12/schema"

addedInput schema / additionalProperties
```
Added value: +false
```

addedInput schema / properties / account_id / description

Added value: +"Account ID or email address. Omit when only one account is signed in."

addedInput schema / properties / account_id / maxLength
```
Added value: +320
```
addedInput schema / properties / account_id / minLength
```
Added value: +1
```

addedInput schema / properties / attachments

Added value: +{
+  "description": "Local files to attach: at most 10, each at most 25 MB.",
+  "items": {
+    "description": "Local file path inside the server's allowed folders. Hidden and secret files are refused.",
+    "maxLength": 4096,
+    "minLength": 1,
+    "type": "string"
+  },
+  "maxItems": 10,
+  "type": "array",
+  "uniqueItems": true
+}

addedInput schema / properties / body / description
```
Added value: +"Reply text."
```
addedInput schema / properties / body / maxLength
```
Added value: +1000000
```
addedInput schema / properties / body / minLength
```
Added value: +1
```

addedInput schema / properties / body_format

Added value: +{
+  "default": "text",
+  "description": "Format of the body text you supply.",
+  "enum": [
+    "text",
+    "html"
+  ],
+  "type": "string"
+}

addedInput schema / properties / cc

Added value: +{
+  "description": "Extra Cc recipients.",
+  "items": {
+    "description": "Email address, e.g. jane@example.com.",
+    "format": "email",
+    "maxLength": 320,
+    "minLength": 3,
+    "type": "string"
+  },
+  "maxItems": 500,
+  "type": "array",
+  "uniqueItems": true
+}

addedInput schema / properties / confirm / description

Added value: +"Must be true to send this reply; set only after the user approves."

addedInput schema / properties / email_id / description
```
Added value: +"Email to reply to."
```
addedInput schema / properties / email_id / maxLength
```
Added value: +1024
```
addedInput schema / properties / email_id / minLength
```
Added value: +1
```

addedInput schema / properties / mode

Added value: +{
+  "description": "sender: reply to the sender. all: reply all.",
+  "enum": [
+    "sender",
+    "all"
+  ],
+  "type": "string"
+}

changedInput schema / required

Previous value: -[
-  "account_id",
-  "email_id",
-  "body"
-]New value: +[
+  "email_id",
+  "mode",
+  "body",
+  "confirm"
+]

addedOutput schema / $schema

Added value: +"https://json-schema.org/draft/2020-12/schema"

changedOutput schema / additionalProperties

Previous value: -{
-  "type": "string"
-}New value: +false

addedOutput schema / description
```
Added value: +"Reply confirmation."
```

addedOutput schema / properties

Added value: +{
+  "conversation_id": {
+    "anyOf": [
+      {
+        "type": "string"
+      },
+      {
+        "type": "null"
+      }
+    ]
+  },
+  "in_reply_to": {
+    "type": "string"
+  },
+  "mode": {
+    "enum": [
+      "sender",
+      "all"
+    ]
+  },
+  "status": {
+    "const": "sent"
+  },
+  "summary": {
+    "description": "One-line human summary. The tool's text content is this result serialized as JSON (summary included), so a client that ignores structuredContent still sees every field.",
+    "type": "string"
+  }
+}

addedOutput schema / required

Added value: +[
+  "status",
+  "mode",
+  "in_reply_to",
+  "conversation_id",
+  "summary"
+]

First observedv0.2.3Jun 10, 2026

TDQS

A4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=false, idempotentHint=false, openWorldHint=true, so the mutation profile is covered. The description adds genuinely new behavior beyond the schema: the confirm-after-user-approval gate and the return of the joined conversation, both of which affect how the agent sequences the call.

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?

Three short sentences, front-loaded with the action and mode split, then the approval prerequisite, then the return. Every clause carries information and nothing is padded.

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?

With an output schema present, return values need not be explained, and annotations cover the safety profile; the description adds the approval gate that the schema alone only implies. Complete enough for correct invocation, though it omits any note about attachment limits or account selection that a caller might want surfaced.

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%, so every parameter including mode, confirm, and attachments is already documented in the schema. The description restates mode and confirm semantics without adding syntax, limits, or resolution behavior beyond what the schema provides; 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 (reply) and resource (an email), and splits the scope into the two mode values, so an agent can distinguish it from email_send or email_forward. It stops short of naming those siblings as alternatives, so differentiation is implicit 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 the condition that selects each mode ('sender' vs 'all') and a hard usage gate: 'Requires confirm=true after the user approves the reply.' It does not contrast this tool with email_forward or email_send, so the agent gets clear context but no explicit exclusions.

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