Create a manual Memory Checkpoint only when the user explicitly asks for a checkpoint or backup. Checkpoints are bounded durable-memory backups; automatic conversation provenance uses snapshots instead.
AI agents use crystal_checkpoint to create or update resources in Memory Crystal MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Memory Crystal MCP Server environment.
This tool writes/creates persistent memory checkpoints. While not destructive (reversible via crystal_edit or crystal_forget), it modifies the agent's persistent state store. The severity is medium because misuse could pollute memory with incorrect information across sessions, but it's bounded to checkpoints rather than real-time data and doesn't delete, execute code, or move money.
From the tool's definition Tool creates 'durable-memory backups' and 'checkpoints' — explicitly described as persistent storage operations that capture and store state. The word 'Create' in the description indicates data modification/creation.
Documented attack patterns abuse exactly the kind of access crystal_checkpoint 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_checkpoint:
{
"version": "1",
"default": "deny",
"tools": {
"crystal_checkpoint": {
"limits": [
{
"counter": "crystal_checkpoint_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}crystal_checkpoint stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Create a manual Memory Checkpoint only when the user explicitly asks for a checkpoint or backup. Checkpoints are bounded durable-memory backups; automatic conversation provenance uses snapshots instead. It is categorised as a Write tool in the Memory Crystal MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Memory Crystal MCP Server MCP server in PolicyLayer and add a rule for crystal_checkpoint: 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_checkpoint is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the crystal_checkpoint 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_checkpoint. 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_checkpoint 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.