publish_topic · Rosbridge MCP Server MCP: Risk & Policy

WHAT IT DOES

What publish_topic does on Rosbridge MCP Server

AI agents invoke publish_topic to trigger actions in Rosbridge MCP Server. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why publish_topic needs a policy

Publishing to a ROS topic sends commands to a live robotics system (motors, actuators, sensors, navigation, etc.). The effects are external and entirely argument-dependent — a misused publish could move a robot arm, change locomotion, or trigger unsafe physical actions.

From the tool's definition 'Publish a message to a ROS topic via rosbridge' — triggers external operations on a ROS-based robotics system whose effects depend on the message arguments

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

publish_topic Rate-limited

publish_topic stays usable, but rate-capped — a runaway agent can't fire it dozens of times 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_topic": {
      "limits": [
        {
          "counter": "publish_topic_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Rosbridge MCP Server, so you can run agents against it safely.

FAQ

Questions about publish_topic

What does the publish_topic tool do? +

Publish a message to a ROS topic via rosbridge. It is categorised as a Execute tool in the Rosbridge MCP Server MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on publish_topic? +

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

What risk level is publish_topic? +

publish_topic is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit publish_topic? +

Yes. Add a rate_limit block to the publish_topic 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_topic completely? +

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

publish_topic is provided by the Rosbridge MCP Server MCP server (takanarishimbo/rosbridge-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.