create_chat · Teams MCP: Risk & Policy

WHAT IT DOES

What create_chat does on Teams

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

WHY IT NEEDS A POLICY

Why create_chat needs a policy

This tool creates (writes) new chat data in Teams, which is a reversible action. It does not execute code, delete data, or handle finances. The severity is medium because creating chats on behalf of a user could be used for spam, social engineering, or unwanted communication campaigns, but the blast radius is limited to the chat system without affecting other data or systems.

From the tool's definition Tool name is 'create_chat' and description states 'Create a new chat conversation' — explicitly creates a new communication channel with one or more users.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

create_chat Rate-limited

create_chat 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": {
    "create_chat": {
      "limits": [
        {
          "counter": "create_chat_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

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

FAQ

Questions about create_chat

What does the create_chat tool do? +

Create a new chat conversation. Can be a 1:1 chat (with one other user) or a group chat (with multiple users). Group chats can optionally have a topic. It is categorised as a Write tool in the Teams MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on create_chat? +

Register the Teams MCP server in PolicyLayer and add a rule for create_chat: 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. Nothing to install.

What risk level is create_chat? +

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

Can I rate-limit create_chat? +

Yes. Add a rate_limit block to the create_chat 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 create_chat completely? +

Set action: deny in the PolicyLayer policy for create_chat. 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 create_chat? +

create_chat is provided by the Teams MCP server (@floriscornel/teams-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.