stbl_write · Stability MCP Server MCP: Risk & Policy

WHAT IT DOES

What stbl_write does on Stability MCP Server

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

WHY IT NEEDS A POLICY

Why stbl_write needs a policy

This tool sends messages to a blockchain, which constitutes a Write operation (creating/modifying on-chain data). Blockchain writes are irreversible by nature, but the description says 'send a message' rather than delete/destroy, so Destructive is not the best fit. However, misuse could have significant consequences since blockchain state changes are permanent — hence high severity.

From the tool's definition 'Send a message to the Stability blockchain' — writes data to the blockchain

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

stbl_write Rate-limited

stbl_write 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": {
    "stbl_write": {
      "limits": [
        {
          "counter": "stbl_write_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 Stability MCP Server, so you can run agents against it safely.

FAQ

Questions about stbl_write

What does the stbl_write tool do? +

Send a message to the Stability blockchain. It is categorised as a Write tool in the Stability MCP 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 stbl_write? +

Register the Stability MCP Server MCP server in PolicyLayer and add a rule for stbl_write: 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 Stability MCP Server. Nothing to install.

What risk level is stbl_write? +

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

Can I rate-limit stbl_write? +

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

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

stbl_write is provided by the Stability MCP Server MCP server (nuljui/stbl-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.