Gets the list of available categories (color-coded labels) for your mailbox. Use this to see what categories can be applied to emails.
AI agents call get-master-categories to retrieve information from Outlook MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This is a read-only query operation that returns metadata about available categories in the user's mailbox. It has no side effects, cannot modify or delete data, and poses minimal risk even if called unnecessarily or repeatedly by an AI agent. The blast radius is negligible.
From the tool's definition The tool 'get-master-categories' retrieves a list of available categories/labels for the mailbox. The description states it 'Gets the list' and is used to 'see what categories can be applied' — purely informational with no modification, deletion, or execution…
Attacks that exploit this kind of access
Gets the list of available categories (color-coded labels) for your mailbox. Use this to see what categories can be applied to emails. It is categorised as a Read tool in the Outlook MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Outlook MCP Server MCP server in PolicyLayer and add a rule for get-master-categories: 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 Outlook MCP Server. Nothing to install.
get-master-categories is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the get-master-categories 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 get-master-categories. 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.
get-master-categories is provided by the Outlook MCP Server MCP server (peacockery-studio/outlook-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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