Turn lights on or off

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

Beyond the annotations (readOnlyHint false), the description discloses exactly what happens: 'off' stops the LEDs, and 'on' resumes movie playback. This clarifies the powered-on state and prevents assumptions about restoring previous states. It adds valuable behavioral context not present in the schema or annotations.

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

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

Two sentences, front-loaded with the purpose, and no wasted words. Every sentence adds meaning: the first states the action, the second clarifies the behavior and directs to the correct alternative.

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

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

This is a simple tool with two parameters (one required) and no output schema. The description fully explains what the tool does, the meaning of 'on' and 'off', and when to use a different tool. No return values are needed, and the device parameter is covered by the schema. The description is complete for this complexity.

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

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

Schema coverage is 100%, with the 'on' parameter already explaining 'true to turn the lights on (movie mode), false to turn them off.' The description adds a bit of nuance ('on resumes movie playback') but does not significantly exceed what the schema already provides. The device parameter is also covered in the schema. Baseline 3 is appropriate.

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

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

The description clearly states the tool turns a Twinkly device on or off, using a specific verb and resource. It also distinguishes itself from sibling tools by pointing to set_mode for specific modes, so there is no ambiguity about its scope.

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

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

The description explicitly provides an alternative when a specific mode is needed: 'For a specific mode like a static color or the demo loop, use set_mode.' This tells the agent when to use this tool versus a sibling, which is strong usage guidance.

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