AI agents call clear_history to permanently remove resources in MCP Mathematics — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
Clearing history is a destructive, irreversible action — once history is purged it cannot be recovered. While the blast radius is limited to session/calculation history rather than financial or system-critical data, the action cannot be undone, placing it in the Destructive category with medium severity.
From the tool's definition Tool name 'clear_history' and description 'Clear history' indicate irreversible deletion of calculation history data.
Documented attack patterns abuse exactly the kind of access clear_history gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Mathematics, and nothing reaches the server without passing your rules. This is the rule we recommend for clear_history:
{
"version": "1",
"default": "deny",
"hide": [
"clear_history"
]
}clear_history disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.
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Clear history. It is categorised as a Destructive tool in the MCP Mathematics MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the MCP Mathematics MCP server in PolicyLayer and add a rule for clear_history: 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 Mathematics. Nothing to install.
clear_history is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.
Yes. Add a rate_limit block to the clear_history 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 clear_history. 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.
clear_history is provided by the MCP Mathematics MCP server (shsharkar/mcp-mathematics). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Mathematics, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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18 MCP Mathematics tools catalogued and risk-classified — across an index of 43,000+ MCP servers.