send_channel_message
Send messages to Microsoft Teams channels with text, markdown formatting, mentions, attachments, and importance levels for team communication.
Instructions
Send a message to a specific channel in a Microsoft Team. Supports text and markdown formatting, mentions, and importance levels.
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| teamId | Yes | Team ID | |
| channelId | Yes | Channel ID | |
| message | Yes | Message content | |
| importance | No | Message importance | |
| format | No | Message format (text or markdown) | |
| mentions | No | Array of @mentions to include in the message | |
| imageUrl | No | URL of an image to attach to the message | |
| imageData | No | Base64 encoded image data to attach | |
| imageContentType | No | MIME type of the image (e.g., 'image/jpeg', 'image/png') | |
| imageFileName | No | Name for the attached image file |
Implementation Reference
- src/tools/teams.ts:242-419 (handler)The main handler function that executes the tool: processes input (text/markdown, mentions, images), uses Microsoft Graph API to post the message to the channel, handles errors and returns success/error response.
async ({ teamId, channelId, message, importance = "normal", format = "text", mentions, imageUrl, imageData, imageContentType, imageFileName, }) => { try { const client = await graphService.getClient(); // Process message content based on format let content: string; let contentType: "text" | "html"; if (format === "markdown") { content = await markdownToHtml(message); contentType = "html"; } else { content = message; contentType = "text"; } // Process @mentions if provided const mentionMappings: Array<{ mention: string; userId: string; displayName: string }> = []; if (mentions && mentions.length > 0) { // Convert provided mentions to mappings with display names for (const mention of mentions) { try { // Get user info to get display name const userResponse = await client .api(`/users/${mention.userId}`) .select("displayName") .get(); mentionMappings.push({ mention: mention.mention, userId: mention.userId, displayName: userResponse.displayName || mention.mention, }); } catch (_error) { console.warn( `Could not resolve user ${mention.userId}, using mention text as display name` ); mentionMappings.push({ mention: mention.mention, userId: mention.userId, displayName: mention.mention, }); } } } // Process mentions in HTML content let finalMentions: Array<{ id: number; mentionText: string; mentioned: { user: { id: string } }; }> = []; if (mentionMappings.length > 0) { const result = processMentionsInHtml(content, mentionMappings); content = result.content; finalMentions = result.mentions; // Ensure we're using HTML content type when mentions are present contentType = "html"; } // Handle image attachment const attachments: ImageAttachment[] = []; if (imageUrl || imageData) { let imageInfo: { data: string; contentType: string } | null = null; if (imageUrl) { imageInfo = await imageUrlToBase64(imageUrl); if (!imageInfo) { return { content: [ { type: "text" as const, text: `ā Failed to download image from URL: ${imageUrl}`, }, ], isError: true, }; } } else if (imageData && imageContentType) { if (!isValidImageType(imageContentType)) { return { content: [ { type: "text" as const, text: `ā Unsupported image type: ${imageContentType}`, }, ], isError: true, }; } imageInfo = { data: imageData, contentType: imageContentType }; } if (imageInfo) { const uploadResult = await uploadImageAsHostedContent( graphService, teamId, channelId, imageInfo.data, imageInfo.contentType, imageFileName ); if (uploadResult) { attachments.push(uploadResult.attachment); } else { return { content: [ { type: "text" as const, text: "ā Failed to upload image attachment", }, ], isError: true, }; } } } // Build message payload const messagePayload: any = { body: { content, contentType, }, importance, }; if (finalMentions.length > 0) { messagePayload.mentions = finalMentions; } if (attachments.length > 0) { messagePayload.attachments = attachments; } const result = (await client .api(`/teams/${teamId}/channels/${channelId}/messages`) .post(messagePayload)) as ChatMessage; // Build success message const successText = `ā Message sent successfully. Message ID: ${result.id}${ finalMentions.length > 0 ? `\nš± Mentions: ${finalMentions.map((m) => m.mentionText).join(", ")}` : "" }${attachments.length > 0 ? `\nš¼ļø Image attached: ${attachments[0].name}` : ""}`; return { content: [ { type: "text" as const, text: successText, }, ], }; } catch (error: any) { return { content: [ { type: "text" as const, text: `ā Failed to send message: ${error.message}`, }, ], isError: true, }; } } - src/tools/teams.ts:217-241 (schema)Zod input schema validating parameters like teamId, channelId, message, optional importance, format, mentions array, and image attachment fields.
{ teamId: z.string().describe("Team ID"), channelId: z.string().describe("Channel ID"), message: z.string().describe("Message content"), importance: z.enum(["normal", "high", "urgent"]).optional().describe("Message importance"), format: z.enum(["text", "markdown"]).optional().describe("Message format (text or markdown)"), mentions: z .array( z.object({ mention: z .string() .describe("The @mention text (e.g., 'john.doe' or 'john.doe@company.com')"), userId: z.string().describe("Azure AD User ID of the mentioned user"), }) ) .optional() .describe("Array of @mentions to include in the message"), imageUrl: z.string().optional().describe("URL of an image to attach to the message"), imageData: z.string().optional().describe("Base64 encoded image data to attach"), imageContentType: z .string() .optional() .describe("MIME type of the image (e.g., 'image/jpeg', 'image/png')"), imageFileName: z.string().optional().describe("Name for the attached image file"), }, - src/tools/teams.ts:214-420 (registration)MCP server.tool registration call that defines the tool name, description, input schema, and handler function.
server.tool( "send_channel_message", "Send a message to a specific channel in a Microsoft Team. Supports text and markdown formatting, mentions, and importance levels.", { teamId: z.string().describe("Team ID"), channelId: z.string().describe("Channel ID"), message: z.string().describe("Message content"), importance: z.enum(["normal", "high", "urgent"]).optional().describe("Message importance"), format: z.enum(["text", "markdown"]).optional().describe("Message format (text or markdown)"), mentions: z .array( z.object({ mention: z .string() .describe("The @mention text (e.g., 'john.doe' or 'john.doe@company.com')"), userId: z.string().describe("Azure AD User ID of the mentioned user"), }) ) .optional() .describe("Array of @mentions to include in the message"), imageUrl: z.string().optional().describe("URL of an image to attach to the message"), imageData: z.string().optional().describe("Base64 encoded image data to attach"), imageContentType: z .string() .optional() .describe("MIME type of the image (e.g., 'image/jpeg', 'image/png')"), imageFileName: z.string().optional().describe("Name for the attached image file"), }, async ({ teamId, channelId, message, importance = "normal", format = "text", mentions, imageUrl, imageData, imageContentType, imageFileName, }) => { try { const client = await graphService.getClient(); // Process message content based on format let content: string; let contentType: "text" | "html"; if (format === "markdown") { content = await markdownToHtml(message); contentType = "html"; } else { content = message; contentType = "text"; } // Process @mentions if provided const mentionMappings: Array<{ mention: string; userId: string; displayName: string }> = []; if (mentions && mentions.length > 0) { // Convert provided mentions to mappings with display names for (const mention of mentions) { try { // Get user info to get display name const userResponse = await client .api(`/users/${mention.userId}`) .select("displayName") .get(); mentionMappings.push({ mention: mention.mention, userId: mention.userId, displayName: userResponse.displayName || mention.mention, }); } catch (_error) { console.warn( `Could not resolve user ${mention.userId}, using mention text as display name` ); mentionMappings.push({ mention: mention.mention, userId: mention.userId, displayName: mention.mention, }); } } } // Process mentions in HTML content let finalMentions: Array<{ id: number; mentionText: string; mentioned: { user: { id: string } }; }> = []; if (mentionMappings.length > 0) { const result = processMentionsInHtml(content, mentionMappings); content = result.content; finalMentions = result.mentions; // Ensure we're using HTML content type when mentions are present contentType = "html"; } // Handle image attachment const attachments: ImageAttachment[] = []; if (imageUrl || imageData) { let imageInfo: { data: string; contentType: string } | null = null; if (imageUrl) { imageInfo = await imageUrlToBase64(imageUrl); if (!imageInfo) { return { content: [ { type: "text" as const, text: `ā Failed to download image from URL: ${imageUrl}`, }, ], isError: true, }; } } else if (imageData && imageContentType) { if (!isValidImageType(imageContentType)) { return { content: [ { type: "text" as const, text: `ā Unsupported image type: ${imageContentType}`, }, ], isError: true, }; } imageInfo = { data: imageData, contentType: imageContentType }; } if (imageInfo) { const uploadResult = await uploadImageAsHostedContent( graphService, teamId, channelId, imageInfo.data, imageInfo.contentType, imageFileName ); if (uploadResult) { attachments.push(uploadResult.attachment); } else { return { content: [ { type: "text" as const, text: "ā Failed to upload image attachment", }, ], isError: true, }; } } } // Build message payload const messagePayload: any = { body: { content, contentType, }, importance, }; if (finalMentions.length > 0) { messagePayload.mentions = finalMentions; } if (attachments.length > 0) { messagePayload.attachments = attachments; } const result = (await client .api(`/teams/${teamId}/channels/${channelId}/messages`) .post(messagePayload)) as ChatMessage; // Build success message const successText = `ā Message sent successfully. Message ID: ${result.id}${ finalMentions.length > 0 ? `\nš± Mentions: ${finalMentions.map((m) => m.mentionText).join(", ")}` : "" }${attachments.length > 0 ? `\nš¼ļø Image attached: ${attachments[0].name}` : ""}`; return { content: [ { type: "text" as const, text: successText, }, ], }; } catch (error: any) { return { content: [ { type: "text" as const, text: `ā Failed to send message: ${error.message}`, }, ], isError: true, }; } } );