MCP Tools Reference: home.googleapis.com

Tool: list_home_states

Retrieves the current states of home resources including devices.

The following code sample shows how to use curl to call the list_home_states MCP tool.

Curl Request 
curl --location 'https://home.googleapis.com/mcp' \
--header 'Authorization: Bearer {oauth-access-token}' \
--header 'content-type: application/json' \
--header 'accept: application/json, text/event-stream' \
--data '{
  "method": "tools/call",
  "params": {
    "name": "list_home_states",
    "arguments": {
      // Provide these details according to the MCP tool specification.
    }
  },
  "jsonrpc": "2.0",
  "id": 1
}'

Input Schema

Request for RetrieveHomeStates.

RetrieveHomeStatesRequest

JSON representation 
{
  "structureId": string,
  "filter": {
    object (Filter)
  },
  "freshness": enum (Freshness)
}
Fields
structureId

string

Optional. The unique identifier for the structure. If omitted, states for all structures and structureless devices for the user will be retrieved.
filter

object (Filter)

Optional. An optional field mask for the device state. The shortened_resource_events field is not supported for RetrieveHomeStates and should not be used.
freshness

enum (Freshness)

Optional. The freshness level of the state to retrieve.

Filter

JSON representation 
{
  "resourceIds": [
    string
  ],
  "shortenedResourceTypes": [
    string
  ],
  "shortenedResourceTraits": [
    string
  ],
  "shortenedResourceEvents": [
    string
  ],
  "fieldPaths": [
    string
  ]
}
Fields
resourceIds[]

string

Optional. The resource id for filtering. (e.g. device@device_id, automation@automation_id)
shortenedResourceTypes[]

string

Optional. The resource types to filter resources by. Example: "GoogleLightDevice", "GoogleDisplayDevice", "SpeakerDevice", "VideoRemoteControlDevice" (and not "action.devices.types.LIGHT"). Not case sensitive.
shortenedResourceTraits[]

string

Optional. The resource traits to filter resources by. Component prefixes should not be included and should be specified in the shortened_resource_types field instead. Example: "OnOff", "Volume" (and not either "home.uddm.traits.matter.OnOffTrait" or "GoogleTvDevice/OnOff"). Not case sensitive.
shortenedResourceEvents[]

string

Optional. The resource events to filter history events by. Must be in "TraitName.EventName" format (e.g. CameraHistory.HistoryItem). Should not be prefixed by component name. Not case sensitive.
fieldPaths[]

string

Optional. Paths to filter by. These are case sensitive. Traits and events should be properly PascalCased and fields should be camelCased.

Format: - For traits: "[Trait].[fieldPath]" - For events: "[Trait].[Event].[fieldPath]"

Examples: - "OnOff.onOff" (or "OnOff.state.onOff") - "CameraHistory.HistoryItem.eventTracks.zones"

For the path filter to take effect, the trait or event type must also be specified in shortened_resource_traits or shortened_resource_events respectively.

Freshness

Freshness levels for state retrieval to balance latency and accuracy.

Enums
FRESHNESS_UNSPECIFIED will be treated as DEFAULT.
DEFAULT Uses report-state-quality heuristics to decide whether to call through to the partner or use home graph data. Recommended for standard reactive prompts.
STALE_READ Reads from the cache (e.g., readobjects or Spanner) which may be stale. Useful for configuration data or general exploration where low latency is prioritized.
MOST_FRESH Bypasses caches and forces a direct query to the partner cloud. Mandatory for high-sensitivity or high-stakes actions like door locks.

Output Schema

Response for RetrieveHomeStates.

RetrieveHomeStatesResponse

JSON representation 
{
  "states": [
    {
      object (ResourceState)
    }
  ]
}
Fields
states[]

object (ResourceState)

The list of home states.

ResourceState

JSON representation 
{
  "id": string,
  "type": string,
  "displayName": string,
  "traits": {
    string: {
      object (TraitState)
    },
    ...
  },
  "resourceConnectivityState": enum (ConnectivityState),
  "timestamp": string
}
Fields
id

string

Identifier. The unique identifier for the resource (e.g. device@device_id, scene@scene_id, automation@automation_id, room@room_id, etc.).
type

string

Output only. The type of the resource.
displayName

string

Output only. The display name of the resource.
traits

map (key: string, value: object (TraitState))

Output only. The state of each trait on the resource, keyed by the trait name (e.g. OnOff, Volume).

An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.
resourceConnectivityState

enum (ConnectivityState)

Output only. The connectivity status of a home resource.
timestamp

string (Timestamp format)

Output only. The timestamp at which the resource state was recorded. For state retrieval, it is the timestamp at which the state was observed.

Uses RFC 3339, where generated output will always be Z-normalized and use 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted. Examples: "2014-10-02T15:01:23Z", "2014-10-02T15:01:23.045123456Z" or "2014-10-02T15:01:23+05:30".

TraitsEntry

JSON representation 
{
  "key": string,
  "value": {
    object (TraitState)
  }
}
Fields
key

string
value

object (TraitState)

TraitState

JSON representation 
{
  "type": string,
  "connectivityState": enum (ConnectivityState),
  "stateReportingOmitted": boolean,
  "state": {
    object
  },
  "timestamp": string
}
Fields
type

string

Output only. The type that this trait applies to.
connectivityState

enum (ConnectivityState)

Output only. The connectivity status of the trait.
stateReportingOmitted

boolean

Output only. Whether the state reporting is omitted for this trait.
state

object (Struct format)

Output only. The state of the trait.
timestamp

string (Timestamp format)

Output only. The timestamp at which the event happened.

Uses RFC 3339, where generated output will always be Z-normalized and use 0, 3, 6 or 9 fractional digits. Offsets other than "Z" are also accepted. Examples: "2014-10-02T15:01:23Z", "2014-10-02T15:01:23.045123456Z" or "2014-10-02T15:01:23+05:30".

Struct

JSON representation 
{
  "fields": {
    string: value,
    ...
  }
}
Fields
fields

map (key: string, value: value (Value format))

Unordered map of dynamically typed values.

An object containing a list of "key": value pairs. Example: { "name": "wrench", "mass": "1.3kg", "count": "3" }.

FieldsEntry

JSON representation 
{
  "key": string,
  "value": value
}
Fields
key

string
value

value (Value format)

Value

JSON representation 
{

  // Union field kind can be only one of the following:
  "nullValue": null,
  "numberValue": number,
  "stringValue": string,
  "boolValue": boolean,
  "structValue": {
    object
  },
  "listValue": array
  // End of list of possible types for union field kind.
}
Fields
Union field kind. The kind of value. kind can be only one of the following:
nullValue

null

Represents a JSON null.
numberValue

number

Represents a JSON number. Must not be NaN, Infinity or -Infinity, since those are not supported in JSON. This also cannot represent large Int64 values, since JSON format generally does not support them in its number type.
stringValue

string

Represents a JSON string.
boolValue

boolean

Represents a JSON boolean (true or false literal in JSON).
structValue

object (Struct format)

Represents a JSON object.
listValue

array (ListValue format)

Represents a JSON array.

ListValue

JSON representation 
{
  "values": [
    value
  ]
}
Fields
values[]

value (Value format)

Repeated field of dynamically typed values.

Timestamp

JSON representation 
{
  "seconds": string,
  "nanos": integer
}
Fields
seconds

string (int64 format)

Represents seconds of UTC time since Unix epoch 1970-01-01T00:00:00Z. Must be between -62135596800 and 253402300799 inclusive (which corresponds to 0001-01-01T00:00:00Z to 9999-12-31T23:59:59Z).
nanos

integer

Non-negative fractions of a second at nanosecond resolution. This field is the nanosecond portion of the duration, not an alternative to seconds. Negative second values with fractions must still have non-negative nanos values that count forward in time. Must be between 0 and 999,999,999 inclusive.

ConnectivityState

The connectivity status of a home resource or trait.

Enums
CONNECTIVITY_STATE_UNSPECIFIED The default value. This value is used if the connectivity status is omitted.
UNKNOWN The connectivity status is unknown.
ONLINE The connectivity status is online.
OFFLINE The connectivity status is offline.
PARTIAL_ONLINE The resource is partially online, meaning some of its underlying functionalities are online.

NullValue

Represents a JSON null.

NullValue is a sentinel, using an enum with only one value to represent the null value for the Value type union.

A field of type NullValue with any value other than 0 is considered invalid. Most ProtoJSON serializers will emit a Value with a null_value set as a JSON null regardless of the integer value, and so will round trip to a 0 value.

Enums
NULL_VALUE Null value.

Tool Annotations

Tool annotations are sent to MCP clients to describe the basic risk of a given tool. Most clients treat these hints as untrusted, but they can be used to decide when a confirmation prompt might be sent to a user.

Along with the title string, the following boolean hints are defined as follows:

  • readOnlyHint: If true, the tool doesn't modify its environment. Default: false.
  • destructiveHint: If true, then the tool can perform destructive actions. If false, then the tool can only perform additive actions. Default: true.
  • idempotentHint: If true, then calling the tool repeatedly with the same arguments will have no additional effect on its environment. Default: false.
  • openWorldHint: If true, then the tool can interact with an 'open world' of external entities. If false, then the tool can only interact with internal entities. For example, a web search tool would be open world, while a memory tool would not be open world.

Destructive Hint: ❌ | Idempotent Hint: ✅ | Read Only Hint: ✅ | Open World Hint: ✅