AI agents call browse_vault_structure to retrieve information from Obsidian MCP Server without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool is purely informational: it lists or navigates the directory structure of an Obsidian vault. No data is created, modified, deleted, or executed. The operation is read-only with no side effects. Severity is low because directory structure metadata alone poses minimal risk even if accessed by an untrusted agent.
From the tool's definition Tool performs 'browse vault directory structure'—a retrieval operation that queries the hierarchical organization of the vault without modifying, executing, or deleting anything.
Documented attack patterns abuse exactly the kind of access browse_vault_structure 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 browse_vault_structure:
{
"version": "1",
"default": "deny",
"tools": {
"browse_vault_structure": {}
}
}browse_vault_structure is read-only, so it stays allowed — but everything else on the server is denied unless you say otherwise.
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Browse vault directory structure. It is categorised as a Read tool in the Obsidian MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Obsidian MCP Server MCP server in PolicyLayer and add a rule for browse_vault_structure: 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.
browse_vault_structure 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 browse_vault_structure 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 browse_vault_structure. 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.
browse_vault_structure is provided by the Obsidian MCP Server MCP server (pmmvr/obsidian-api-mcp-server). 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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3 Obsidian MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.