Calculate duration between two times
AI agents call calculate_duration to retrieve information from MCP Time Server Node without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and processes temporal data to compute a difference, analogous to a time query or arithmetic lookup. It does not create, modify, delete, or execute external operations. The worst-case misuse is returning incorrect time information, which poses minimal risk to systems or data.
From the tool's definition Tool performs a calculation between two times with no modification of state or external data. Description states 'Calculate duration between two times' — a pure computational query with no side effects.
Attacks that exploit this kind of access
Calculate duration between two times. It is categorised as a Read tool in the MCP Time Server Node MCP Server, which means it retrieves data without modifying state.
Register the MCP Time Server Node MCP server in PolicyLayer and add a rule for calculate_duration: 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 Time Server Node. Nothing to install.
calculate_duration 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 calculate_duration 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 calculate_duration. 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.
calculate_duration is provided by the MCP Time Server Node MCP server (pshempel/mcp-time-server-node). 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.
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