send_channel · Agent Bus MCP: Risk & Policy

WHAT IT DOES

What send_channel does on Agent Bus

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

WHY IT NEEDS A POLICY

Why send_channel needs a policy

This tool creates and transmits messages to channel subscribers, which is a Write operation (data creation/modification with reversible effects). Severity is medium because misuse could flood channels, disrupt agent workflows, or send unintended communications to multiple agents, but messages are typically not destructive or irreversible.

From the tool's definition Tool name 'send_channel' and description 'Broadcast a message to every subscriber of a channel' indicate creation/transmission of data to multiple recipients.

Risk signalsBulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

send_channel Rate-limited

send_channel 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": {
    "send_channel": {
      "limits": [
        {
          "counter": "send_channel_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 Agent Bus, so you can run agents against it safely.

FAQ

Questions about send_channel

What does the send_channel tool do? +

Broadcast a message to every subscriber of a channel. It is categorised as a Write tool in the Agent Bus MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on send_channel? +

Register the Agent Bus MCP server in PolicyLayer and add a rule for send_channel: 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 Agent Bus. Nothing to install.

What risk level is send_channel? +

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

Can I rate-limit send_channel? +

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

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

send_channel is provided by the Agent Bus MCP server (mustaphasteph/agent-bus). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.