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

Annotations already establish that this is a safe, closed-world read (readOnlyHint true, destructiveHint false, openWorldHint false), so the safety profile is covered. The description adds a useful boundary — this is explanatory, not a quote or site assessment — but says nothing about what a response contains or how the explanatory content is scoped. Adequate, not rich.

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, zero filler. The positive trigger comes first, the scope details second, and the do-not-use clause last, which is the right ordering for an agent scanning for routing cues.

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, single-optional-parameter explanation tool with no output schema, the description supplies enough to select and invoke it correctly. The only material omission is which sibling to use instead when the user actually wants a quote, savings estimate, or site assessment.

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%, and the single optional 'question' parameter is fully documented in the schema, including the PII refusal behavior and the empty-value behavior. The description adds nothing beyond that, which is acceptable at full coverage but caps the score at baseline.

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?

Names a specific verb and subject (explaining rooftop solar) and narrows the scope to bill mechanics: imports, exports, and STCs. This is far more specific than the sibling explain_* tools, though it never explicitly contrasts itself with estimate_bill_savings or compare_scenarios, which sit closest to the same topic.

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?

Gives an explicit trigger ("Use this when explaining how rooftop solar meets a household bill") plus an explicit exclusion ("Do not use this as a quote or a site assessment"). It stops short of pointing the agent at the correct sibling tool for quoting or assessment work, so routing is only partly resolved.

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