AI agents call ha_list_states to retrieve information from Hass without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves and lists the current states of Home Assistant entities. It is purely informational—it reads data without creating, modifying, deleting, or executing any state-changing actions. The note that output 'can be large' reflects only data volume, not risk severity. Classification as Read is appropriate with high confidence.
From the tool's definition Tool name 'ha_list_states' and description 'List Home Assistant entity states' indicate querying/retrieval of state data with no modification, deletion, or execution of operations.
Attacks that exploit this kind of access
List Home Assistant entity states (can be large). It is categorised as a Read tool in the Hass MCP Server, which means it retrieves data without modifying state.
Register the Hass MCP server in PolicyLayer and add a rule for ha_list_states: 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 Hass. Nothing to install.
ha_list_states 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 ha_list_states 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 ha_list_states. 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.
ha_list_states is provided by the Hass MCP server (thewhykiki/hass-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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