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homeassistant-ai

Home Assistant MCP Server

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Python
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Manage Frontend Themes

ha_manage_theme
DestructiveIdempotent

List installed Home Assistant themes and set the backend default theme for light or dark mode; also inspect or restore the screenshot account's per-user theme after a screenshot changes it.

Instructions

Manage Home Assistant frontend themes.

When NOT to use: themes are YAML files - Home Assistant has no API to create or edit them. Installing community themes goes through HACS (ha_manage_hacs); editing custom theme files goes through ha_config_set_yaml (beta, edits themes/.yaml keyed by theme name and attempts an automatic theme reload).

When to use: action='list' discovers installed theme names and the current defaults; action='set' selects the backend default theme (optionally per light/dark mode).

SCREENSHOT-ENGINE ACTIONS (per-user, not the backend default): Taking a dashboard screenshot makes the Puppet engine write the saved theme of the Home Assistant user its token belongs to, which also flips that user's live web and mobile sessions. The screenshot tools are read-only and only report this; use action='set_engine_theme' with the value quoted in their warning to put it back, and action='get_engine_theme' to inspect it. These act on that engine account's per-user profile via frontend/set_user_data, which is a different layer from the backend default that action='set' changes. Giving the engine its own dedicated user and token avoids the issue entirely.

Caveats: action='set' changes the backend-selected default only - users who explicitly picked a theme in their profile keep their choice. Theme names are validated by Home Assistant at call time.

EXAMPLES:

  • List themes: ha_manage_theme(action="list")

  • Set default theme: ha_manage_theme(action="set", theme_name="nord")

  • Set dark-mode theme: ha_manage_theme( action="set", theme_name="nord", mode="dark")

  • Restore built-in default: ha_manage_theme( action="set", theme_name="default")

  • Inspect the engine account's theme: ha_manage_theme( action="get_engine_theme")

  • Undo a screenshot's theme change (pass BOTH values from the warning, so a theme changed since then is not overwritten): ha_manage_theme(action="set_engine_theme", value={"theme": "", "dark": False}, expected_current={"theme": "default", "dark": True})

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
modeNoWhich mode the theme applies to when action='set'. Defaults to light.
forceNoaction='set_engine_theme' only: skip the expected_current guard and overwrite unconditionally. Leave false unless you intend to discard whatever is stored.
valueNoFrontend user-data theme object when action='set_engine_theme', e.g. {'theme': '', 'dark': False}. An empty dict restores default/auto behavior. Take this verbatim from the warning a screenshot tool emitted.
actionYesTheme operation: 'list' installed themes, 'set' the backend default theme, or read/restore the screenshot engine account's own per-user theme with 'get_engine_theme' / 'set_engine_theme' (a different layer from the backend default).
theme_nameNoTheme name when action='set'. Must be an installed theme; 'default' restores the built-in theme, 'none' resets the chosen mode to the built-in default.
expected_currentNoGuard for action='set_engine_theme': the stored theme is read immediately before the write and the write is skipped if it no longer equals this. Omitting this value or passing null both mean 'expect no stored theme', enforced like any other value; the guard is always applied unless force is set. Best-effort, not atomic -- Home Assistant exposes no conditional write, so a change landing between that read and the write is not caught. Pass the expected_current value quoted in the screenshot tool's warning.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. Changed5 schema fields changedv8.4.1
    • changedInput schema / properties / action / description
      Previous value: -"Theme operation: list installed themes or set the default theme."New value: +"Theme operation: 'list' installed themes, 'set' the backend default theme, or read/restore the screenshot engine account's own per-user theme with 'get_engine_theme' / 'set_engine_theme' (a different layer from the backend default)."
    • changedInput schema / properties / action / enum
      Previous value: -[
-  "list",
-  "set"
-]New value: +[
+  "list",
+  "set",
+  "get_engine_theme",
+  "set_engine_theme"
+]
    • addedInput schema / properties / expected_current
      Added value: +{
+  "anyOf": [
+    {
+      "additionalProperties": true,
+      "type": "object"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Guard for action='set_engine_theme': the stored theme is read immediately before the write and the write is skipped if it no longer equals this. Omitting this value or passing null both mean 'expect no stored theme', enforced like any other value; the guard is always applied unless force is set. Best-effort, not atomic -- Home Assistant exposes no conditional write, so a change landing between that read and the write is not caught. Pass the expected_current value quoted in the screenshot tool's warning."
+}
    • addedInput schema / properties / force
      Added value: +{
+  "default": false,
+  "description": "action='set_engine_theme' only: skip the expected_current guard and overwrite unconditionally. Leave false unless you intend to discard whatever is stored.",
+  "type": "boolean"
+}
    • addedInput schema / properties / value
      Added value: +{
+  "anyOf": [
+    {
+      "additionalProperties": true,
+      "type": "object"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Frontend user-data theme object when action='set_engine_theme', e.g. {'theme': '', 'dark': False}. An empty dict restores default/auto behavior. Take this verbatim from the warning a screenshot tool emitted."
+}
  2. First observedv7.14.2

TDQS

A4.8/5.0
Behavior5/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description goes well beyond the annotations, explaining that action='set' affects only the backend default and that users with explicit theme choices keep theirs. It also discloses that screenshot-engine theme changes flip live user sessions, that the expected_current guard is best-effort and non-atomic, and that force skips the guard. This is rich, honest behavioral context that does not contradict the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is long but well-structured with clear sections and examples. It front-loads the core purpose and usage guidance. Some details are repeated from the schema, and the screenshot-engine section is verbose, but the complexity of the tool justifies much of the length.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with four distinct actions, multiple parameter guards, and a screenshot-engine interaction, the description covers all necessary context: when to use, caveats, examples, and behavioral warnings. An output schema exists, so return values do not need to be explained. Nothing essential is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3. The description adds value with concrete examples, guidance to pass value verbatim from screenshot warnings, and clarification of the expected_current guard semantics. It largely reinforces the schema rather than introducing entirely new meaning, so a 4 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the resource (Home Assistant frontend themes) and the specific operations: listing installed themes, setting the backend default, and managing the screenshot engine account's per-user theme. It also distinguishes itself from related tools like ha_manage_hacs and ha_config_set_yaml by explicitly stating what it is not for.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides explicit 'When NOT to use' and 'When to use' guidance, naming alternatives for editing theme files and installing community themes. It also gives detailed context for when to use each action, including the screenshot-engine scenario.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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