open_tag · MCP Bear MCP: Risk & Policy

WHAT IT DOES

What open_tag does on MCP Bear

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

WHY IT NEEDS A POLICY

Why open_tag needs a policy

An AI agent can call open_tag faster than any human can review — one bad instruction and it creates or modifies resources in MCP Bear by the hundred, each call as confident as the last.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

open_tag Rate-limited

open_tag 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": {
    "open_tag": {
      "limits": [
        {
          "counter": "open_tag_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 Bear, so you can run agents against it safely.

FAQ

Questions about open_tag

What does the open_tag tool do? +

Open Bear and show all notes with a specific tag. It is categorised as a Write tool in the MCP Bear MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on open_tag? +

Register the MCP Bear MCP server in PolicyLayer and add a rule for open_tag: 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 Bear. Nothing to install.

What risk level is open_tag? +

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

Can I rate-limit open_tag? +

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

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

open_tag is provided by the MCP Bear MCP server (maxim-ist/mcp-bear). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.