item_update · Mcp 1password MCP: Risk & Policy

WHAT IT DOES

What item_update does on Mcp 1password

AI agents use item_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 item_update needs a policy

This tool creates or modifies data reversibly within 1Password vaults. While it alters sensitive credential storage (high blast radius if misused by an agent), it is not destructive (item remains recoverable) and not financial. The risk is primarily from unintended modifications to vault items, making it Write severity:high rather than Execute or Destructive.

From the tool's definition Tool name 'item_update' and description 'Update an item. Provided arrays replace the existing arrays on the item.' indicates modification of existing data in 1Password vaults. The replacement semantics show it modifies but does not delete items irreversibly.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

item_update Rate-limited

item_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": {
    "item_update": {
      "limits": [
        {
          "counter": "item_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 item_update

What does the item_update tool do? +

Update an item. Provided arrays replace the existing arrays on the item. 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 item_update? +

Register the Mcp 1password MCP server in PolicyLayer and add a rule for item_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 item_update? +

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

Can I rate-limit item_update? +

Yes. Add a rate_limit block to the item_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 item_update completely? +

Set action: deny in the PolicyLayer policy for item_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 item_update? +

item_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.