MCP Tools Reference: chatmcp.googleapis.com

Tool: send_message

Sends a Google Chat message to a conversation.

This tool uses a conversation ID, an optional thread ID, and a message text as inputs. Conversation ID's can be found using the search_conversations tool. It returns the created message.

The following sample demonstrate how to use curl to invoke the send_message MCP tool.

Curl Request 
curl --location 'https://chatmcp.googleapis.com/mcp/v1' \
--header 'content-type: application/json' \
--header 'accept: application/json, text/event-stream' \
--data '{
  "method": "tools/call",
  "params": {
    "name": "send_message",
    "arguments": {
      // provide these details according to the tool MCP specification
    }
  },
  "jsonrpc": "2.0",
  "id": 1
}'

Input Schema

Request to send a message to a Google Chat conversation.

SendMessageRequest

JSON representation 
{
  "conversationId": string,
  "threadId": string,
  "messageText": string
}
Fields
conversationId

string

Required. The ID of the conversation (e.g., 'spaces/AAAA...') to send the message to.
threadId

string

Optional. The ID of the thread (e.g., 'spaces/AAAA.../threads/BBBB...') to send the message to. If not set, the message will be sent to a new thread.
messageText

string

Required. The main content of the message. Basic formatting can be added using a subset of Markdown. For information about how to format messages, see Format messages. The following formatting is supported:

  • Bold: *text*
  • Italic: _text_
  • Strikethrough: ~text~
  • Monospace: text
  • Monospace block:
```
line 1
line 2
```
  • Bulleted list:
* item 1
* item 2
  • Block quote: > quoted text
  • Hyperlink: <url|display text>
  • Mention user: <users/{user_id}>

Output Schema

Response to sending a message to a Google Chat conversation.

SendMessageResponse

JSON representation 
{
  "message": {
    object (ChatMessage)
  }
}
Fields
message

object (ChatMessage)

The message that was sent.

ChatMessage

JSON representation 
{
  "messageId": string,
  "threadId": string,
  "plaintextBody": string,
  "sender": {
    object (User)
  },
  "createTime": string,
  "threadedReply": boolean,
  "attachments": [
    {
      object (ChatAttachmentMetadata)
    }
  ],
  "reactionSummaries": [
    {
      object (ReactionSummary)
    }
  ]
}
Fields
messageId

string

Resource name of the message. Format: spaces/{space}/messages/{message}
threadId

string

The thread this message belongs to. This will be empty if the message is unthreaded. Format: spaces/{space}/threads/{thread}
plaintextBody

string

Plain text body of the message.
sender

object (User)

The sender of the message.
createTime

string

Output only. Timestamp when the message was created.
threadedReply

boolean

Whether message is a thread reply.
attachments[]

object (ChatAttachmentMetadata)

Attachments included in the message.
reactionSummaries[]

object (ReactionSummary)

The emoji reactions summary included in the message.

User

JSON representation 
{
  "userId": string,
  "displayName": string,
  "email": string,
  "userType": enum (UserType)
}
Fields
userId

string

Resource name of a Chat user. Format: users/{user}.
displayName

string

The display name of a Chat user.
email

string

The email address of the user. This field is only populated when the user type is HUMAN.
userType

enum (UserType)

The type of the user.

ChatAttachmentMetadata

JSON representation 
{
  "attachmentId": string,
  "filename": string,
  "mimeType": string,
  "source": enum (Source)
}
Fields
attachmentId

string

Resource name of the attachment. Format: spaces/{space}/messages/{message}/attachments/{attachment}.
filename

string

Name of the attachment.
mimeType

string

Content type (MIME type).
source

enum (Source)

The source of the attachment.

ReactionSummary

JSON representation 
{
  "emoji": string,
  "count": integer
}
Fields
emoji

string

The emoji unicode string or custom emoji name.
count

integer

The total number of reactions using the associated emoji.

UserType

The type of a Google Chat user.

Enums
USER_TYPE_UNSPECIFIED Unspecified.
HUMAN Human user.
APP App user.

Source

The source of the attachment.

Enums
SOURCE_UNSPECIFIED Reserved.
DRIVE_FILE The file is a Google Drive file.
UPLOADED_CONTENT The file is uploaded to Chat.

Tool Annotations

Destructive Hint: ❌ | Idempotent Hint: ❌ | Read Only Hint: ❌ | Open World Hint: ✅