device-control

Home Assistant Device Control

Use the homeassistant-manager MCP server tools to control and query all devices in Home Assistant.

Core Tool: ha_call_service

ha_call_service is the universal action tool. Most device control flows through it.

Structure:

• domain — device type (light, switch, climate, media_player, cover, lock, fan, vacuum, etc.)
• service — what to do (turn_on, turn_off, toggle, set_temperature, etc.)
• entity_id — target entity
• service_data — extra parameters (brightness, color_temp, temperature, etc.)

Common Device Workflows

Lights

turn_on: domain=light, service=turn_on, entity_id=light.living_room
dim to 50%: service_data={brightness_pct: 50}
warm white: service_data={color_temp_kelvin: 2700}
color: service_data={rgb_color: [255, 0, 0]}
turn off all: entity_id=all (with domain=light)

Switches & Plugs

domain=switch, service=turn_on/turn_off/toggle

Climate / Thermostat

set temp: domain=climate, service=set_temperature, service_data={temperature: 72}
set mode: domain=climate, service=set_hvac_mode, service_data={hvac_mode: "heat"/"cool"/"auto"/"off"}
set fan: domain=climate, service=set_fan_mode, service_data={fan_mode: "auto"/"low"/"high"}

Locks

lock:   domain=lock, service=lock
unlock: domain=lock, service=unlock

Covers (blinds, garage doors, curtains)

open:    domain=cover, service=open_cover
close:   domain=cover, service=close_cover
set pos: domain=cover, service=set_cover_position, service_data={position: 50}

Media Players

play:   domain=media_player, service=media_play
pause:  domain=media_player, service=media_pause
volume: domain=media_player, service=volume_set, service_data={volume_level: 0.5}
source: domain=media_player, service=select_source, service_data={source: "Spotify"}

Fans

turn on/off:  domain=fan, service=turn_on/turn_off
speed:        domain=fan, service=set_percentage, service_data={percentage: 50}
oscillate:    domain=fan, service=oscillate, service_data={oscillating: true}

Vacuum

start:  domain=vacuum, service=start
return: domain=vacuum, service=return_to_base
pause:  domain=vacuum, service=pause

Querying Devices

• ha_get_states with a domain filter — list all entities of a type
• ha_get_state — check a specific entity's state and attributes
• ha_render_template — compute values from state data (e.g. average temperature)

Finding Entity IDs

If the user doesn't know an entity ID:

1. Call ha_get_states with the relevant domain
2. Match by attributes.friendly_name to find the right entity
3. Use that entity_id

Reference

See references/domains-and-services.md for the full list of domains, services, and service data fields.