contact_update · M365 MCP: Risk & Policy

WHAT IT DOES

What contact_update does on M365

AI agents use contact_update to create or update resources in M365 — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your M365 environment.

WHY IT NEEDS A POLICY

Why contact_update needs a policy

Based on naming convention and server context, contact_update creates or modifies contact records reversibly, fitting the Write category. Severity is medium because unauthorized contact modifications could affect communication routing, but lack complete destructive or financial impact. Confidence is reduced due to the empty tool description; a populated description would improve certainty.

From the tool's definition Tool name 'contact_update' indicates modification of contact data. The server description states it 'manage[s] Microsoft 365 services' including 'Contacts through natural language commands.' The tool description is empty, limiting full assessment.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

contact_update Rate-limited

contact_update 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": {
    "contact_update": {
      "limits": [
        {
          "counter": "contact_update_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 M365, so you can run agents against it safely.

FAQ

Questions about contact_update

What does the contact_update tool do? +

contact_update. It is categorised as a Write tool in the M365 MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on contact_update? +

Register the M365 MCP server in PolicyLayer and add a rule for contact_update: 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 M365. Nothing to install.

What risk level is contact_update? +

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

Can I rate-limit contact_update? +

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

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

contact_update is provided by the M365 MCP server (robin-collins/m365-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.