set_active_vault · Obsidian MCP Server MCP: Risk & Policy

WHAT IT DOES

What set_active_vault does on Obsidian MCP Server

AI agents use set_active_vault 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.

WHY IT NEEDS A POLICY

Why set_active_vault needs a policy

Setting an active vault modifies the operational state of the Obsidian context—subsequent tools will operate against the newly selected vault. This is a state-changing Write operation, not a destructive action, since vault selection is reversible.

From the tool's definition Tool name is 'set_active_vault' which modifies state by selecting an active vault. Server description mentions 'multi-vault support' indicating vault switching is a stateful operation.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

set_active_vault Rate-limited

set_active_vault 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.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_active_vault": {
      "limits": [
        {
          "counter": "set_active_vault_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Obsidian MCP Server, so you can run agents against it safely.

FAQ

Questions about set_active_vault

What does the set_active_vault tool do? +

set_active_vault. 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.

How do I enforce a policy on set_active_vault? +

Register the Obsidian MCP Server MCP server in PolicyLayer and add a rule for set_active_vault: 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.

What risk level is set_active_vault? +

set_active_vault is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_active_vault? +

Yes. Add a rate_limit block to the set_active_vault 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.

How do I block set_active_vault completely? +

Set action: deny in the PolicyLayer policy for set_active_vault. 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.

What MCP server provides set_active_vault? +

set_active_vault is provided by the Obsidian MCP Server MCP server (nbaradar/obsidian-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.