listen_state_changes
Listen for state change events for an entity. Returns up to count events within timeout seconds.
This record as markdown: /tools/fistacho-ha-nexus-agent/listen-state-changes.md
What listen_state_changes does on Ha Nexus Agent
AI agents call listen_state_changes to retrieve information from Ha Nexus Agent without modifying anything. It is typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
Why listen_state_changes is rated Low
This tool queries and returns event data without creating, modifying, deleting, or triggering any changes to the smart home system. It is a passive listener that retrieves historical or real-time state change events. The severity is low because even if misused, an AI agent can only read information about entity state changes with no ability to control devices or alter system state.
From the tool's definition Tool description states it 'Listen for state change events for an entity' and 'Returns up to `count` events' — this is purely observational/retrieval of state data with no modifications or side effects.
Attacks that exploit this kind of access
The rule that runs listen_state_changes safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Ha Nexus Agent, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For listen_state_changes, this is the rule to start with:
listen_state_changes is read-only, so it stays allowed. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect Ha Nexus Agent, apply this rule, and every listen_state_changes call is checked against it from then on.
Questions about listen_state_changes
Listen for state change events for an entity. Returns up to count events within timeout seconds. It is categorised as a Read tool in the Ha Nexus Agent MCP Server, which means it retrieves data without modifying state.
Register the Ha Nexus Agent MCP server in PolicyLayer and add a rule for listen_state_changes: 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 Ha Nexus Agent. Nothing to install.
listen_state_changes 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 listen_state_changes 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 listen_state_changes. 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.
listen_state_changes is provided by the Ha Nexus Agent MCP server (fistacho/ha-nexus-agent). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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