AI agents call crystal_recent to retrieve information from Memory Crystal MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool appears to retrieve recent memory or conversation context without modifying data. The lack of explicit description limits confidence slightly, but the naming pattern and server context (memory retrieval/injection) indicate a read operation. No destructive, financial, or code execution indicators are present.
From the tool's definition Tool name 'crystal_recent' with no description provided. Context indicates this Memory Crystal server is designed for capturing and retrieving persistent memory and knowledge.
Documented attack patterns abuse exactly the kind of access crystal_recent gives an agent:
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_recent:
{
"version": "1",
"default": "deny",
"tools": {
"crystal_recent": {}
}
} crystal_recent is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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crystal_recent. It is categorised as a Read tool in the Memory Crystal MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Memory Crystal MCP Server MCP server in PolicyLayer and add a rule for crystal_recent: 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.
crystal_recent is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the crystal_recent 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 crystal_recent. 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.
crystal_recent 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.
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.
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31 Memory Crystal MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.