teams_send_message · Teams MCP Server MCP: Risk & Policy

WHAT IT DOES

What teams_send_message does on Teams MCP Server

AI agents use teams_send_message to create or update resources in Teams MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Teams MCP Server environment.

WHY IT NEEDS A POLICY

Why teams_send_message needs a policy

This tool creates new data (messages) in Teams conversations, which is reversible through deletion (teams_delete_message exists as a sibling tool). It does not execute arbitrary code, delete data irreversibly, or move money. The severity is medium because sending messages could facilitate phishing, misinformation, or spam, but the blast radius is limited to communication channels rather than system-wide impact.

From the tool's definition Tool name 'teams_send_message' and description 'Send a message to a Teams conversation' indicate this creates new message data in a reversible manner. The markdown formatting reference confirms message composition and posting capability.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

teams_send_message Rate-limited

teams_send_message stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "teams_send_message": {
      "limits": [
        {
          "counter": "teams_send_message_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Teams MCP Server, so you can run agents against it safely.

FAQ

Questions about teams_send_message

What does the teams_send_message tool do? +

Send a message to a Teams conversation. Use markdown for formatting (not HTML): bold, *italic*, ~~strikethrough~~,. It is categorised as a Write tool in the Teams MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on teams_send_message? +

Register the Teams MCP Server MCP server in PolicyLayer and add a rule for teams_send_message: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Teams MCP Server. Nothing to install.

What risk level is teams_send_message? +

teams_send_message is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit teams_send_message? +

Yes. Add a rate_limit block to the teams_send_message rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block teams_send_message completely? +

Set action: deny in the PolicyLayer policy for teams_send_message. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides teams_send_message? +

teams_send_message is provided by the Teams MCP Server MCP server (m0nkmaster/msteams-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.