AI agents call list_journals to retrieve information from MCP-DayOne without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool queries and returns a list of journals without creating, modifying, deleting, or executing any operations. It is a straightforward read operation with minimal security risk; exposure would only allow an agent to discover which journals exist, not access their contents or make changes.
From the tool's definition Tool name is 'list_journals' and description states 'List all available Day One journals' — a retrieval operation with no modification or side effects.
Documented attack patterns abuse exactly the kind of access list_journals gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP-DayOne, and nothing reaches the server without passing your rules. This is the rule we recommend for list_journals:
{
"version": "1",
"default": "deny",
"tools": {
"list_journals": {}
}
}list_journals is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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List all available Day One journals. It is categorised as a Read tool in the MCP-DayOne MCP Server, which means it retrieves data without modifying state.
Register the MCP-DayOne MCP server in PolicyLayer and add a rule for list_journals: 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 MCP-DayOne. Nothing to install.
list_journals 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 list_journals 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 list_journals. 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.
list_journals is provided by the MCP-DayOne MCP server (quevin/mcp-dayone). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP-DayOne, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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10 MCP-DayOne tools catalogued and risk-classified — across an index of 43,000+ MCP servers.