Set device color (hex)

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

With annotations already covering readOnlyHint=false, destructiveHint=false, and idempotentHint=true, the safety profile is established. The description adds the valuable insight that it builds the URL-encoded JSON map with Hubitat's hex extension — a non-obvious behavioral/internal detail, and warns 'Nobody constructs this by hand correctly,' justifying why the tool exists. This exceeds the annotation baseline.

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?

Four tight sentences with zero waste. Action first, implementation detail second, usage guidance third, exclusion last. Every sentence earns its place.

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?

For a 2-param tool with 100% schema coverage, an output schema, and solid annotations, the description is nearly complete. It covers purpose, usage boundaries, and internal implementation nuance. It could mention response format, but the output schema likely compensates, so only a minor gap remains.

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 description coverage is 100%, covering both device_id and hex with clear descriptions. The description adds the color-format details (#RRGGBB or RRGGBB) and the hex-extension JSON construction context, which enriches understanding beyond the schema. Baseline 3 is appropriate since the schema handles parameter documentation well.

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 states a specific verb+resource: "Set a ColorControl device color from a hex string." It clearly distinguishes from siblings (hubitat_send_command handles generic commands, this handles color specifically) and even calls out the unique hex-extension formatting.

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?

Explicit when-to-use: 'Use when: setting bulb color from #RRGGBB or RRGGBB' and explicit when-not: 'Do NOT use when: only changing level or on/off.' This gives the agent clear decision boundaries and implies alternatives for level/on-off changes.

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