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set_light

Control a single Hue light's brightness, color temperature, color xy, effect, gradient, timed effect, and transition settings. Pass only attributes to update.

Instructions

Update one light. Pass only the attributes you want to change.

Use list_lights() to discover what each light supports — it returns effects.available, timed_effects.available, and (for gradient strips) a gradient block with points_capable and mode_values.

  • brightness is 0–100 (percent). Setting brightness on an off light does NOT turn it on; pass on=True as well.

  • color_temp_mirek is the CIE mired value; the per-light valid range is reported by list_lights() as color_temp_range_mirek (commonly 153–500, i.e. ~6500K–2000K). Setting this clears any active colour.

  • color_xy is a 2-element list [x, y] in CIE 1931 colour space, clamped to the light's gamut. Setting this clears any active colour temperature.

  • effect is one of the values from effects.available (e.g. no_effect, candle, fire, prism, sparkle, opal, glisten). Pass no_effect to stop a running effect.

  • gradient_points is a list of [x, y] CIE 1931 points (typically 2–5, capped by the light's gradient.points_capable). Only meaningful for gradient-capable strips like the Hue Play Gradient lightstrip.

  • gradient_mode is one of the light's gradient.mode_valuesinterpolated_palette (default smooth blend), interpolated_palette_mirrored, random_pixelated, or segmented_palette.

  • timed_effect is sunrise, sunset, or no_effect. Use timed_effect_duration_ms to set how long the effect runs.

  • transition_ms is the fade duration in milliseconds for on/off, dimming, and colour changes.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
onNo
effectNo
color_xyNo
light_idYes
brightnessNo
timed_effectNo
gradient_modeNo
transition_msNo
gradient_pointsNo
color_temp_mirekNo
timed_effect_duration_msNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Behavior5/5

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

No annotations exist, so the description carries full burden. It explicitly discloses key behaviors: brightness doesn't turn on the light, color settings clear each other, effect values are listed, gradient points only work on capable strips, and transition_ms controls fade duration.

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 well-structured with a clear lead sentence and bullet-point parameter details. It is lengthy but necessary given 11 parameters. Minor redundancy exists (e.g., 'Pass only the attributes you want to change' could be implicit).

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?

Given the existence of an output schema and no annotations, the description covers all necessary information: parameter semantics, behavioral constraints, and cross-references to list_lights for capability discovery. It is complete for a tool with 11 parameters.

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

Parameters5/5

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

With 0% schema description coverage, the description fully compensates by detailing every parameter: brightness range 0-100, color_temp_mirek valid range from list_lights, color_xy as [x,y] in CIE 1931, effect examples, gradient_points format, gradient_mode values, timed_effect options, and transition_ms in milliseconds.

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 opens with 'Update one light. Pass only the attributes you want to change,' which is a specific verb+resource statement. It clearly distinguishes from sibling tools like list_lights and set_group.

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

Usage Guidelines4/5

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

The description advises using list_lights() to discover light capabilities and notes that setting brightness on an off light does not turn it on. However, it does not explicitly state when not to use this tool or name alternatives for group/scene operations.

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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