List color IDs for calendars and events
AI agents call list-colors to retrieve information from Google Calendar MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves metadata about available color options for calendars and events. It is a read-only query that does not create, modify, delete, or execute any operations. The low severity reflects minimal risk even in misuse, as color metadata retrieval cannot impact calendar data integrity or trigger unwanted actions.
From the tool's definition Tool name 'list-colors' and description 'List color IDs for calendars and events' indicate a retrieval operation with no side effects.
Attacks that exploit this kind of access
List color IDs for calendars and events. It is categorised as a Read tool in the Google Calendar MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Google Calendar MCP Server MCP server in PolicyLayer and add a rule for list-colors: 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 Google Calendar MCP Server. Nothing to install.
list-colors 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 list-colors 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 list-colors. 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.
list-colors is provided by the Google Calendar MCP Server MCP server (progrmoiz/cal-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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