teams_add_reaction · Teams MCP Server MCP: Risk & Policy

WHAT IT DOES

What teams_add_reaction does on Teams MCP Server

AI agents use teams_add_reaction 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_add_reaction needs a policy

Adding a reaction creates a new data element (the reaction) and modifies the message's state reversibly. This is a classic Write operation: the action can be undone by removing the reaction, and it has no destructive, financial, or code-execution implications. Severity is low because reactions are cosmetic and low-impact user-facing metadata with minimal blast radius.

From the tool's definition Tool description states 'Add an emoji reaction to a message' — this creates a new reaction object associated with a message, modifying the message's reaction state in Teams.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

teams_add_reaction Rate-limited

teams_add_reaction 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_add_reaction": {
      "limits": [
        {
          "counter": "teams_add_reaction_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

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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_add_reaction

What does the teams_add_reaction tool do? +

Add an emoji reaction to a message. Common reactions: like (👍), heart (❤️), laugh (😂), surprised (😮), sad (😢), angry (😠). Use teams_search_emoji to find other emojis. 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_add_reaction? +

Register the Teams MCP Server MCP server in PolicyLayer and add a rule for teams_add_reaction: 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_add_reaction? +

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

Can I rate-limit teams_add_reaction? +

Yes. Add a rate_limit block to the teams_add_reaction 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_add_reaction completely? +

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

teams_add_reaction 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.