Delete the index for a repository, forcing a full re-index on the next index_repo or index_folder call.
AI agents call invalidate_cache to permanently remove resources in Astllm — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.
This tool destroys cached index data without the ability to recover it. While the data can be rebuilt via re-indexing, the action itself is irreversible and destructive in nature. The impact is moderate rather than critical because: (1) the underlying source code remains intact, (2) re-indexing is automatic on next use, and (3) this primarily affects performance/caching rather than source data.
From the tool's definition The description explicitly states the tool will "Delete the index for a repository", which is an irreversible destructive action. The phrase "forcing a full re-index" confirms the deletion is permanent and cannot be undone without rebuilding.
Attacks that exploit this kind of access
Delete the index for a repository, forcing a full re-index on the next index_repo or index_folder call. It is categorised as a Destructive tool in the Astllm MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.
Register the Astllm MCP server in PolicyLayer and add a rule for invalidate_cache: 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 Astllm. Nothing to install.
invalidate_cache 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 invalidate_cache 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 invalidate_cache. 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.
invalidate_cache is provided by the Astllm MCP server (tluyben/astllm-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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