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

Beyond the readOnly/idempotent annotations, the description discloses output content (missing unpriced work and a data confidence signal) and sets expectations that the returned range is not a contractor quote, national average, or guarantee. It doesn't state pricing basis, region coverage limits, or what happens when a required boolean is unknown.

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 short front-loaded sentences with the capability first, then prerequisites, then caveats; nothing is padded. The final line about an "add-ons-only result" is cryptic in isolation and costs a little clarity for its brevity.

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?

With no output schema and 7 required parameters, the description covers the essentials: currency/region, benchmark source, output contents, and trust caveats. It still leaves the agent guessing how unknown site facts should be encoded and roughly how wide a returned confidence band can be.

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?

Only 1 of 7 parameters carries a schema description (14% coverage), so the schema does little work. The description partially compensates by framing all inputs as "site assumptions" that must be confirmed with the user before selection, but it adds no meaning for productType, sizeClass, permitRequired, panelUpgradeNeeded, foundationNeeded, or deliveryIncluded.

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 first sentence states a specific verb (estimate), resource (planning costs in USD), method (Sauna Guide price benchmarks and installation ranges) and geography (US). It is clearly a planning-range tool rather than a quote check or brand comparison, though it never names a sibling explicitly.

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 site assumptions are required; ask before choosing them" gives a concrete procedural directive, and the closing line rules out mislabeling an add-ons-only result as a total. What's missing is routing against the obvious alternatives (check_sauna_quote, prepare_sauna_quote_request) so the agent must infer the sequence.

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