vault_update · Mcp 1password MCP: Risk & Policy

WHAT IT DOES

What vault_update does on Mcp 1password

AI agents use vault_update to create or update resources in Mcp 1password — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp 1password environment.

WHY IT NEEDS A POLICY

Why vault_update needs a policy

The tool creates or modifies data in a reversible manner (updating vault properties like title and description). While it operates on 1Password vaults which store sensitive credentials, the operation itself is a standard metadata update rather than destructive deletion, code execution, or financial transaction.

From the tool's definition Tool description states: "Update a vault title and/or description." This modifies vault metadata reversibly without deleting data or executing arbitrary operations.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

vault_update Rate-limited

vault_update 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": {
    "vault_update": {
      "limits": [
        {
          "counter": "vault_update_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 Mcp 1password, so you can run agents against it safely.

FAQ

Questions about vault_update

What does the vault_update tool do? +

Update a vault title and/or description. It is categorised as a Write tool in the Mcp 1password MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on vault_update? +

Register the Mcp 1password MCP server in PolicyLayer and add a rule for vault_update: 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 Mcp 1password. Nothing to install.

What risk level is vault_update? +

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

Can I rate-limit vault_update? +

Yes. Add a rate_limit block to the vault_update 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 vault_update completely? +

Set action: deny in the PolicyLayer policy for vault_update. 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 vault_update? +

vault_update is provided by the Mcp 1password MCP server (kefapps/onepassword-mcp-codex). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.