home-assistant.call_service
Control a device by calling a Home Assistant service on explicit entities, e.g. light.turn_on for light.kitchen. Only allowlisted domains/entities are accepted and every call goes through CoWork approval.
This record as markdown: /tools/cowork-os/home-assistant.call-service.md
What home-assistant.call_service does on CoWork OS
AI agents invoke home-assistant.call_service to trigger actions in CoWork OS. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call: builds kicked off, notifications sent, workflows started.
Why home-assistant.call_service is rated High
Triggers external physical device operations with real-world effects beyond data modification.
From the tool's definition Control a device by calling a Home Assistant service
Risk signalsBulk/mass operation — affects multiple targets
Attacks that exploit this kind of access
The rule that runs home-assistant.call_service safely
PolicyLayer is an MCP gateway: it sits between your AI agents and CoWork OS, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For home-assistant.call_service, this is the rule to start with:
home-assistant.call_service stays usable, but rate-capped: a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.
The button opens the PolicyLayer dashboard: create your workspace, connect CoWork OS, apply this rule, and every home-assistant.call_service call is checked against it from then on.
Questions about home-assistant.call_service
Control a device by calling a Home Assistant service on explicit entities, e.g. light.turn_on for light.kitchen. Only allowlisted domains/entities are accepted and every call goes through CoWork approval. It is categorised as a Execute tool in the CoWork OS MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.
Register the CoWork OS MCP server in PolicyLayer and add a rule for home-assistant.call_service: 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 CoWork OS. Nothing to install.
home-assistant.call_service is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the home-assistant.call_service 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 home-assistant.call_service. 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.
home-assistant.call_service is provided by the CoWork OS MCP server (CoWork-OS/CoWork-OS). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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