ALWAYS call this before any config change, API write, file deletion, external message send, or production system modification. Returns relevant rules, lessons, and past decisions as a checklist. Helps prevent repeating mistakes.
AI agents call crystal_preflight 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.
crystal_preflight is a pre-action lookup that queries persistent memory for applicable rules and past decisions. Despite being invoked before destructive or high-risk operations, the tool itself only reads and returns information. Its blast radius if misused is low since it produces no side effects; at worst an agent skips it and loses guardrail context.
From the tool's definition 'Returns relevant rules, lessons, and past decisions as a checklist' — the tool retrieves stored knowledge/context before an action is taken; it does not itself perform any modification.
Documented attack patterns abuse exactly the kind of access crystal_preflight 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_preflight:
{
"version": "1",
"default": "deny",
"tools": {
"crystal_preflight": {}
}
}crystal_preflight is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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ALWAYS call this before any config change, API write, file deletion, external message send, or production system modification. Returns relevant rules, lessons, and past decisions as a checklist. Helps prevent repeating mistakes. 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_preflight: 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_preflight 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_preflight 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_preflight. 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_preflight 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.
Free to start. No card required.
31 Memory Crystal MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.