// MCP TOOL REFERENCE

crystal_forget

ServerMemory Crystal MCP Server
CategoryDestructive

WHAT IT DOES

What crystal_forget does on Memory Crystal MCP Server

AI agents call crystal_forget to permanently remove resources in Memory Crystal MCP Server — typically in cleanup and lifecycle workflows. It does its job in a single call, and there is no undo.

THE RISK

Critical Risk

Why crystal_forget needs a policy

This tool can permanently erase memories/data that cannot be recovered (permanent=false toggles behavior, but permanent=true performs irreversible deletion). Even though archiving is reversible, the core capability to permanently delete data places this in the Destructive category.

From the tool's definition "permanently delete a memory" and "permanent=true only when you are certain the memory should be irretrievably deleted" indicate irreversible deletion of stored data.

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

POLICY

How to control crystal_forget

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

policy.json

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

crystal_forget 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 Memory Crystal 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 Memory Crystal MCP Server tools

Write crystal_capture Capture a memory into Memory Crystal Write crystal_idea_action Take action on a memory discovery -- star it as valuable, dismiss it, or mark it as read. Write crystal_supersede Atomically replace a stale or incorrect memory with a successor. The old memory is archive Write crystal_checkpoint Create a manual Memory Checkpoint only when the user explicitly asks for a checkpoint or b Write crystal_create_knowledge_base Create a Memory Crystal knowledge base. Write crystal_edit Update an existing memory in Memory Crystal. Use to correct errors, add new information, o Write crystal_import_knowledge Import text chunks into a Memory Crystal knowledge base. Write crystal_remember Create a Memory Crystal memory using semantic embedding + vector storage.

All 31 Memory Crystal 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 Memory Crystal 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 crystal_forget

What does the crystal_forget tool do? +

Archive or permanently delete a memory. Use archive (permanent=false, the default) to soft-delete so the memory can be recovered. Use permanent=true only when you are certain the memory should be irretrievably deleted. It is categorised as a Destructive tool in the Memory Crystal 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 crystal_forget? +

Register the Memory Crystal MCP Server MCP server in PolicyLayer and add a rule for crystal_forget: 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 Memory Crystal MCP Server. Nothing to install.

What risk level is crystal_forget? +

crystal_forget 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 crystal_forget? +

Yes. Add a rate_limit block to the crystal_forget 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 crystal_forget completely? +

Set action: deny in the PolicyLayer policy for crystal_forget. 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 crystal_forget? +

crystal_forget is provided by the Memory Crystal MCP Server MCP server (memorycrystal/memorycrystal). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Memory Crystal MCP Server tool call.

Start from Memory Crystal 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 →

Free to start. No card required.

31 Memory Crystal MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.