Live power draw

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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is caught. The description adds value by noting 'Instantaneous only' and explaining what data is returned (breakdown, unattributed load), plus the hardware limitation. This goes beyond mere read-only flags, though not exhaustive on response format since no output schema exists.

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?

The description is two sentences, front-loaded with the core purpose. The first sentence is concise; the second adds necessary context about history and device limitations. Slightly dense but no wasted words, earns a solid 4.

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 read-only tool with 2 parameters and no output schema, the description explains what it returns (watts, breakdowns, unattributed load), clarifies the instantaneous nature, offers alternative history tools with specific guidance, and mentions a hardware-specific caveat. This is complete for an agent to decide when to use it.

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?

The schema covers both parameters completely with descriptions (limit, includeItems). The description does not add parameter-specific details beyond what the schema already provides, so it relies on the schema. This meets the baseline for high schema coverage.

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 it reads current power draw in watts with a room/device breakdown, whole-home meter, and unattributed load. It distinguishes itself from the historical query tool by specifying 'Instantaneous only' and naming the alternative, so purpose is unambiguous.

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?

Explicitly states when to use this tool versus alternatives: 'for history use homey_insights_query' with specific log types (meter_power vs measure_power). It also warns about Homey Pro (Early 2019) lacking historical endpoints, providing clear usage context.

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