publish · Momento MCP Server MCP: Risk & Policy

WHAT IT DOES

What publish does on Momento MCP Server

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

WHY IT NEEDS A POLICY

Why publish needs a policy

Publishing to a topic creates or modifies data in a message queue/pubsub system. While it has side effects and could impact subscribers, it is reversible and does not meet the threshold for Execute (no arbitrary code execution), Destructive (not irreversible deletion), or Financial categories.

From the tool's definition Tool description states 'publish a value to a topic' which performs a write operation to a messaging/pubsub system. The action is reversible (the published message can be ignored or overwritten by subsequent publishes) and does not permanently delete data.

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

publish Rate-limited

publish 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": {
    "publish": {
      "limits": [
        {
          "counter": "publish_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 Momento MCP Server, so you can run agents against it safely.

FAQ

Questions about publish

What does the publish tool do? +

publish a value to a topic. It is categorised as a Write tool in the Momento 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 publish? +

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

What risk level is publish? +

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

Can I rate-limit publish? +

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

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

publish is provided by the Momento MCP Server MCP server (momentohq/mcp-momento). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.