AI agents use add_appointment to create or update resources in MCP Outlook Tools — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Outlook Tools environment.
This tool creates a new calendar event, which is a Write operation (reversible creation). It does not execute arbitrary code, delete data, or move money. The severity is medium because a compromised agent could create numerous fake appointments to clutter calendars or impersonate meeting requests, but the impact is limited to calendar data and appointments can be deleted.
From the tool's definition Tool name 'add_appointment' and description 'Add a new appointment to Outlook calendar' indicate creation of a new calendar entry, which is reversible data modification.
Documented attack patterns abuse exactly the kind of access add_appointment gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Outlook Tools, and nothing reaches the server without passing your rules. This is the rule we recommend for add_appointment:
{
"version": "1",
"default": "deny",
"tools": {
"add_appointment": {
"limits": [
{
"counter": "add_appointment_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}add_appointment 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.
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Add a new appointment to Outlook calendar. It is categorised as a Write tool in the MCP Outlook Tools MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP Outlook Tools MCP server in PolicyLayer and add a rule for add_appointment: 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 MCP Outlook Tools. Nothing to install.
add_appointment is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the add_appointment 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.
Set action: deny in the PolicyLayer policy for add_appointment. 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.
add_appointment is provided by the MCP Outlook Tools MCP server (wmoto-ai/mcp-outlook-tools). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Outlook Tools, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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6 MCP Outlook Tools tools catalogued and risk-classified — across an index of 43,000+ MCP servers.