AI agents call subscribers to retrieve information from Agent Bus without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
The tool performs a straightforward informational retrieval—listing subscribers to a channel. It has no side effects, does not modify data, does not execute code or commands, and does not involve financial transactions. The blast radius of misuse is minimal; an attacker could only learn which agents are subscribed to channels, which is low-impact information in a local collaborative environment.
From the tool's definition Tool name is 'subscribers' and description states it 'List the agents subscribed to a channel.' This is a query operation that retrieves subscription metadata without modifying state or triggering external operations.
Attacks that exploit this kind of access
List the agents subscribed to a channel. It is categorised as a Read tool in the Agent Bus MCP Server, which means it retrieves data without modifying state.
Register the Agent Bus MCP server in PolicyLayer and add a rule for subscribers: 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.
subscribers is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the subscribers 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.
Set action: deny in the PolicyLayer policy for subscribers. 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.
subscribers 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.
subscribers is one line of Agent Bus's registry record.
The record carries the whole server: verified identity, auth posture, risk grade, every tool classified, recommended policy — re-checked continuously.
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