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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the agent knows this is a pure offline calculation with no side effects. The description adds a rough sketch of the computation chain (conduction, kWh conversion, utility cost), but discloses no behavioral details such as the HDD value source, defaulting behavior for r2, or how results are returned. Adds modest value on top of the 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?

A single front-loaded sentence that names the two outputs first and the inputs second, with no filler. It is grammatically a fragment rather than a sentence, but it is dense and wastes nothing.

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, the description must carry the return-value burden, and it does name the two outputs (U-value and annual heating saving). However, it omits units for the result, the heating-degree-day assumption behind the saving estimate, and the default behavior of r2, all of which an agent needs to call and interpret this correctly.

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%, so the schema already documents r1, r2, area, and cost, including that cost=0 disables the dollar estimate. The description adds little beyond restating them and, notably, names 'heating degree days' as an input even though no such parameter exists in the schema, which could confuse the agent. 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 names the concrete outputs (U-value of the upgrade and estimated annual heating saving) and the method (conduction over heating degree days). It is clearly distinguished from numeric siblings like bmr_tdee or roofing, though it never says 'insulation savings calculator' as a plain framing sentence. The purpose is unmistakable but the sentence is phrased as a fragment rather than a statement of what the tool does.

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?

There is no guidance on when to use this versus any alternative, no prerequisites, and no note on assumptions. Nothing tells the agent what context (climate region, building type) the heating-degree-day value assumes, which matters for interpreting results. The description only lists inputs and outputs.

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