add_event

THE RISK

Medium Risk

Why add_event needs a policy

This tool creates new diagram elements (events) within a BPMN document, which is a Write operation—it modifies state reversibly and does not execute external code, delete data, or move funds. The blast radius is medium because uncontrolled event additions could corrupt diagram structure or create confusing/invalid workflows, but changes can be undone by removing the event.

From the tool's definition Tool name is 'add_event' and description states 'Add an event to the current diagram'. The verb 'Add' indicates creation of a new element within a BPMN diagram, which is a reversible modification to the diagram data structure.

Documented attack patterns abuse exactly the kind of access add_event gives an agent:

POLICY

How to control add_event

PolicyLayer is an MCP gateway — it sits between your AI agents and MCP-BPMN Server, and nothing reaches the server without passing your rules. This is the rule we recommend for add_event:

policy.json

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

add_event 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.

Create a free account and register MCP-BPMN Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More MCP-BPMN Server tools

Destructive bpmn_delete_diagram Delete a saved BPMN diagram file Destructive bpmn_delete_element Delete an element from the process Destructive delete_diagram_file Delete a saved BPMN diagram file Destructive delete_element Delete an element from the current diagram Write new_bpmn Create a new BPMN diagram and set it as current context Write new_from_mermaid Create a new BPMN diagram from Mermaid code and set it as current context Write add_activity Add an activity to the current diagram Write add_gateway Add a gateway to the current diagram

All 41 MCP-BPMN Server tools →

Write tools on other servers

M-Team MCP Server download_torrent YouTube MCP Server generate_video_title Android Forensics ADB MCP Server combine_reports 0xarchive web3_signup

Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about add_event

What does the add_event tool do? +

Add an event to the current diagram. It is categorised as a Write tool in the MCP-BPMN 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 add_event? +

Register the MCP-BPMN Server MCP server in PolicyLayer and add a rule for add_event: 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-BPMN Server. Nothing to install.

What risk level is add_event? +

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

Can I rate-limit add_event? +

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

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

add_event is provided by the MCP-BPMN Server MCP server (oisee/mcp-bpmn). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every MCP-BPMN Server tool call.

Start from MCP-BPMN Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →