Clear cached field values to force fresh data loading - use this when table data has changed or cached values are stale
AI agents call discard_table_field_values to permanently remove resources in Metabase MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
The tool irreversibly clears/purges cached field values from the system. While the underlying source data is not deleted, the cached values themselves are permanently removed and cannot be restored (they can only be regenerated). This is a destructive operation on the cache store.
From the tool's definition 'Clear cached field values' - permanently removes cached data; 'force fresh data loading' implies the cached values are irrecoverably discarded
Attacks that exploit this kind of access
Clear cached field values to force fresh data loading - use this when table data has changed or cached values are stale. It is categorised as a Destructive tool in the Metabase MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Metabase MCP Server MCP server in PolicyLayer and add a rule for discard_table_field_values: 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 Metabase MCP Server. Nothing to install.
discard_table_field_values 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 discard_table_field_values 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 discard_table_field_values. 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.
discard_table_field_values is provided by the Metabase MCP Server MCP server (thangnm93/metabase-mcp-server). 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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