AI agents use duplicate_note to create or update resources in Obsidian MCP Server — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Obsidian MCP Server environment.
The tool creates a reversible copy of an existing note. It is a Write action (not Read, as it modifies the vault state by adding content; not Destructive, as duplication is reversible and does not delete or overwrite existing data; not Execute, as it does not run code or commands).
From the tool's definition "Create a copy of a note" — this is a write operation that creates new data (a duplicate note) in the vault.
Documented attack patterns abuse exactly the kind of access duplicate_note gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Obsidian MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for duplicate_note:
{
"version": "1",
"default": "deny",
"tools": {
"duplicate_note": {
"limits": [
{
"counter": "duplicate_note_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}duplicate_note 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 copy of a note. It is categorised as a Write tool in the Obsidian MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Obsidian MCP Server MCP server in PolicyLayer and add a rule for duplicate_note: 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 Obsidian MCP Server. Nothing to install.
duplicate_note 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 duplicate_note 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 duplicate_note. 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.
duplicate_note is provided by the Obsidian MCP Server MCP server (kynlos/obsidian-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Obsidian 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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120 Obsidian MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.