Get historical state changes for an entity
AI agents call get_history to retrieve information from Home Assistant MCP Server 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 about an entity's past state changes. It is a read-only operation that retrieves information without side effects, making it a Read category tool. The severity is low because historical data access poses minimal risk to the home automation system — it does not control devices, modify automations, or execute commands.
From the tool's definition Tool name is 'get_history' and description states 'Get historical state changes for an entity' — this retrieves time-series data without modifying any state or triggering actions.
Attacks that exploit this kind of access
Get historical state changes for an entity. It is categorised as a Read tool in the Home Assistant MCP Server MCP Server, which means it retrieves data without modifying state.
Register the Home Assistant MCP Server MCP server in PolicyLayer and add a rule for 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 Home Assistant MCP Server. Nothing to install.
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 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 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.
get_history is provided by the Home Assistant MCP Server MCP server (mjrestivo16/mcp-homeassistant). 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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