crystal_recall

THE RISK

Low Risk

Why crystal_recall needs a policy

This tool retrieves or queries stored memories without side effects. It fits the Read category: it performs a lookup/fetch operation on persistent memory state. Even though memories may contain sensitive conversation context, the tool itself only retrieves data and does not create, modify, delete, or execute external operations.

From the tool's definition Tool name is 'crystal_recall' and description states 'Recall memories from Memory Crystal' — the verb 'recall' and 'from' indicate data retrieval with no modification or deletion.

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

POLICY

How to control crystal_recall

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_recall:

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "crystal_recall": {}
  }
}

crystal_recall is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.

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.

CAP THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Memory Crystal MCP Server tools

Destructive crystal_forget Archive or permanently delete a memory. Use archive (permanent=false, the default) to soft 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.

All 31 Memory Crystal MCP Server tools →

Read tools on other servers

M-Team MCP Server get_torrent_detail YouTube MCP Server search_channel Android Forensics ADB MCP Server parse_browser_history 0xarchive web3_challenge

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Data exfiltration → How read access becomes an exfiltration channel when chained with untrusted content.
MCP token cost → What connecting this server costs in context-window tokens on every request.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about crystal_recall

What does the crystal_recall tool do? +

Recall memories from Memory Crystal. It is categorised as a Read tool in the Memory Crystal MCP Server MCP Server, which means it retrieves data without modifying state.

How do I enforce a policy on crystal_recall? +

Register the Memory Crystal MCP Server MCP server in PolicyLayer and add a rule for crystal_recall: 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_recall? +

crystal_recall is a Read tool with low risk. Read-only tools are generally safe to allow by default.

Can I rate-limit crystal_recall? +

Yes. Add a rate_limit block to the crystal_recall 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_recall completely? +

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

crystal_recall 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 →