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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint=false, so the safety profile is covered. The description usefully discloses that the tool evaluates RE2020 targets and returns per-element pass flags (walls_ok, roof_ok, floor_ok), but listing the return fields duplicates the existing output schema rather than adding behavioral depth.

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?

Three tight, front-loaded sentences: the formula leads, the compliance comparison follows, then the sibling pointer. Slight redundancy in enumerating return fields that the output schema already defines, but overall efficient.

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 a full output schema present, the description need not explain return values, and it correctly supplies the domain frame (RE2020 compliance) and the governing formula. It is essentially complete for a two-parameter read-only calculator, missing only disambiguation from the similarly named insulation sibling.

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 coverage is 100% and both parameters carry unit-aware descriptions (lambda W/(m·K) with example values, thickness in mm), so the baseline is 3. The formula in the description clarifies how the two inputs relate but adds no syntax or unit detail beyond what the schema already provides.

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?

States a specific verb (Calculate) and resource (thermal R-value) plus the exact formula R = thickness/lambda, so the computation is unambiguous. It does not, however, differentiate itself from the very similarly named sibling calculate_insulation_r, leaving a potential ambiguity an agent cannot resolve from the text.

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?

'Compare with RE2020 targets' implies the French building-regulation compliance use case, which is genuine context. But there is no explicit when-to-use/when-not guidance and no mention of the near-duplicate calculate_insulation_r sibling; the pointer to list_bundles is navigation, not usage guidance.

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