AI agents use multi_file_replace 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.
This tool modifies existing note content in bulk across multiple files. While reversible (can be undone), the batch nature and potential for widespread unintended changes make it high-severity. It does not delete data (would be Destructive) but actively rewrites content (Write category). High confidence due to explicit 'replace' terminology indicating content modification.
From the tool's definition Tool name 'multi_file_replace' and description 'Batch find/replace across multiple notes' indicate modification of file content across multiple documents. The 'replace' operation modifies data reversibly.
Documented attack patterns abuse exactly the kind of access multi_file_replace 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 multi_file_replace:
{
"version": "1",
"default": "deny",
"tools": {
"multi_file_replace": {
"limits": [
{
"counter": "multi_file_replace_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}multi_file_replace 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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Batch find/replace across multiple notes. 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 multi_file_replace: 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.
multi_file_replace 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 multi_file_replace 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 multi_file_replace. 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.
multi_file_replace 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.
Free to start. No card required.
120 Obsidian MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.