AI agents call ha_get_history 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 queries historical data from Home Assistant without modifying, executing, or deleting anything. It is a pure read operation that retrieves timestamped records for audit/analysis purposes. The severity is low because fetching history poses minimal risk—it cannot affect system state or trigger actions.
From the tool's definition Tool name 'ha_get_history' and description 'Fetch history since an ISO time (optionally for an entity)' indicate data retrieval with no modification or side effects.
Attacks that exploit this kind of access
Fetch history since an ISO time (optionally for an entity). 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_get_history: 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_get_history 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_get_history 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_get_history. 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_get_history 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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