clear_index

THE RISK

Critical Risk

Why clear_index needs a policy

Clearing index state and caches is a destructive operation that cannot be easily undone. While not permanently data-destructive at the filesystem level, it irreversibly discards the semantic index and cached analysis results that may have taken significant time to build. Recovery requires a full rebuild. An AI agent misusing this could disrupt development workflows, waste computational resources, and cause delays.

From the tool's definition Tool description states 'Remove saved index state and clear caches' — 'Remove' and 'clear' indicate irreversible deletion of cached data and index state.

Documented attack patterns abuse exactly the kind of access clear_index gives an agent:

POLICY

How to control clear_index

PolicyLayer is an MCP gateway — it sits between your AI agents and Context Engine MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for clear_index:

policy.json

{
  "version": "1",
  "default": "deny",
  "hide": [
    "clear_index"
  ]
}

clear_index disappears from the agent's tool list entirely, and any attempt to call it is denied. The rest of the server keeps working.

Create a free account and register Context Engine MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

RESTRICT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Context Engine MCP Server tools

Destructive delete_plan Delete a saved plan from storage. Destructive reindex_workspace Clear current index state and rebuild it from scratch. Execute execute_plan Execute steps from an implementation plan, generating code changes. This tool orchestrate Execute index_workspace Index the current workspace for semantic search. This tool scans all source files in the Execute reactive_review_pr Start a reactive PR code review session. This tool initiates an AI-powered code review wi Execute run_static_analysis Run local static analyzers (tsc and optional semgrep) and return structured findings. Execute check_invariants Run YAML invariants deterministically against a unified diff (no LLM). Execute pause_review Pause a running reactive review session. The review can be resumed later with resume_revi

All 50 Context Engine MCP Server tools →

Destructive tools on other servers

Android Forensics ADB MCP Server create_full_backup 0xarchive web3_revoke_key Frida Game Hacking MCP clear_scan cPanel MCP Server clear_spam_box

Go deeper

Critical-risk tools in Context Engine MCP Server → Every critical-risk tool this server exposes, in one view.
All critical-risk MCP tools → Every critical-risk tool across the catalogue, and the policy pattern that contains them.
The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Blast radius → How much damage one compromised or confused agent can do — and how to bound it.
Tool call approval → Approval gates on individual tool calls: auto-allow, prompt, or deny.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about clear_index

What does the clear_index tool do? +

Remove saved index state and clear caches without rebuilding. It is categorised as a Destructive tool in the Context Engine MCP Server MCP Server, which means it can permanently delete or destroy data. Block by default and require explicit approval.

How do I enforce a policy on clear_index? +

Register the Context Engine MCP Server MCP server in PolicyLayer and add a rule for clear_index: 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 Context Engine MCP Server. Nothing to install.

What risk level is clear_index? +

clear_index is a Destructive tool with critical risk. Critical-risk tools should be blocked by default and only enabled with explicit human approval.

Can I rate-limit clear_index? +

Yes. Add a rate_limit block to the clear_index 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.

How do I block clear_index completely? +

Set action: deny in the PolicyLayer policy for clear_index. 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.

What MCP server provides clear_index? +

clear_index is provided by the Context Engine MCP Server MCP server (kirachon/context-engine). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Context Engine MCP Server tool call.

Start from Context Engine MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →