Medium Risk

update

update

How to control update ↓

What update does on Prometheus MCP Server

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

Medium Risk

Why update needs a policy

The tool name 'update' indicates data modification capability. Without a description, confidence is reduced, but the sibling tools and Prometheus context suggest this modifies metrics, configurations, or alerts reversibly rather than destructively.

From the tool's definition Tool name is 'update' with empty description. Based on context of AWS Managed Prometheus MCP server and sibling tools that modify state (add_attachments_to_set, add_inline_policy, add_user_to_group), this is likely a Write operation.

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

How to control update

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

policy.json
{
  "version": "1",
  "default": "deny",
  "tools": {
    "update": {
      "limits": [
        {
          "counter": "update_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

update 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.

  1. Create a free account and register Prometheus MCP Server — nothing to install.
  2. Add this policy — paste it, or build it visually.
  3. Point your MCP client (Claude, Cursor, anything) at your gateway URL.
LIMIT THIS TOOL →

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Related tools and policies

Go deeper

Questions about update

What does the update tool do? +

update. It is categorised as a Write tool in the Prometheus 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? +

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

What risk level is update? +

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

Can I rate-limit update? +

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

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

update is provided by the Prometheus MCP Server MCP server (awslabs.prometheus-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Prometheus MCP Server tool call.

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

Free to start. No card required.

805 Prometheus MCP Server tools catalogued and risk-classified — across an index of 43,000+ MCP servers.

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