update_rule · Sablier MCP Server MCP: Risk & Policy

WHAT IT DOES

What update_rule does on Sablier MCP Server

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

WHY IT NEEDS A POLICY

Why update_rule needs a policy

The name clearly indicates a write/modification action ('update'). Without a description, confidence is reduced, but the pattern of sibling tools (backtest_rules, analyze_derivatives) and the server's portfolio/stress-testing purpose suggest this modifies rule configurations rather than executing them. Rules can be modified and reverted, placing this in Write rather than Execute.

From the tool's definition Tool name 'update_rule' indicates modification of existing rules; the verb 'update' denotes a reversible write operation. Description is empty, limiting confidence.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

update_rule Rate-limited

update_rule 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_rule": {
      "limits": [
        {
          "counter": "update_rule_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 Sablier MCP Server, so you can run agents against it safely.

FAQ

Questions about update_rule

What does the update_rule tool do? +

update_rule. It is categorised as a Write tool in the Sablier 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 update_rule? +

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

What risk level is update_rule? +

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

Can I rate-limit update_rule? +

Yes. Add a rate_limit block to the update_rule 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_rule completely? +

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

update_rule is provided by the Sablier MCP Server MCP server (sablier-ai/sablier-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.