update_node · Flowchart MCP: Risk & Policy

WHAT IT DOES

What update_node does on Flowchart MCP

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

WHY IT NEEDS A POLICY

Why update_node needs a policy

The tool creates or modifies data in a reversible manner (characteristic of Write category). Updates to diagram nodes can be undone or corrected by subsequent updates. There is no evidence of code execution, financial impact, irreversible deletion, or data theft. The blast radius is limited to the flowchart being edited.

From the tool's definition Tool name is 'update_node' and description states 'Update an existing node' — this modifies existing data (node properties) reversibly within a flowchart diagram without deletion or irreversible destruction.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_node Rate-limited

update_node 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": {
    "update_node": {
      "limits": [
        {
          "counter": "update_node_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 Flowchart MCP, so you can run agents against it safely.

FAQ

Questions about update_node

What does the update_node tool do? +

Update an existing node. It is categorised as a Write tool in the Flowchart MCP MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on update_node? +

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

What risk level is update_node? +

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

Can I rate-limit update_node? +

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

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

update_node is provided by the Flowchart MCP server (zafer-liu/flowchart_mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.