AI agents use split_note_by_headings 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 new notes (Write category) by programmatically splitting an existing note structure. While reversible and non-destructive on its own, it modifies the vault structure by creating multiple new notes, which could introduce organizational chaos if misapplied at scale.
From the tool's definition Tool name 'split_note_by_headings' and description 'Break large note into smaller ones' indicates creation of new notes by subdividing existing content. This is a reversible modification operation.
Documented attack patterns abuse exactly the kind of access split_note_by_headings 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 split_note_by_headings:
{
"version": "1",
"default": "deny",
"tools": {
"split_note_by_headings": {
"limits": [
{
"counter": "split_note_by_headings_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}split_note_by_headings 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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Break large note into smaller ones. 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 split_note_by_headings: 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.
split_note_by_headings 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 split_note_by_headings 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 split_note_by_headings. 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.
split_note_by_headings 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.