AI agents use journal_write to create or update resources in Celiums Memory — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Celiums Memory environment.
This tool modifies user memory state by adding journal entries in a persistent cognitive memory engine. While reversible (entries could theoretically be deleted), the write operation itself creates new data in a user's personal memory context. This is Write rather than Read (it doesn't just retrieve data) and not Destructive (append is not irreversible deletion).
From the tool's definition Tool name "journal_write" and description "Append a first-person entry to YOUR (the model" clearly indicate creation/modification of persistent journal data. The verb "append" is explicitly a write operation that adds new entries.
Documented attack patterns abuse exactly the kind of access journal_write gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Celiums Memory, and nothing reaches the server without passing your rules. This is the rule we recommend for journal_write:
{
"version": "1",
"default": "deny",
"tools": {
"journal_write": {
"limits": [
{
"counter": "journal_write_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}journal_write 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.
Free to start. No card required.
Append a first-person entry to YOUR (the model\. It is categorised as a Write tool in the Celiums Memory MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Celiums Memory MCP server in PolicyLayer and add a rule for journal_write: 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 Celiums Memory. Nothing to install.
journal_write 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 journal_write 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 journal_write. 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.
journal_write is provided by the Celiums Memory MCP server (terrizoaguimor/celiums-memory). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Celiums Memory, 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.
62 Celiums Memory tools catalogued and risk-classified — across an index of 43,000+ MCP servers.