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

Annotations already cover safety (readOnly, idempotent, non-destructive), yet the description goes further by disclosing the exact computation formula and the output unit (m²·K/W), which is genuinely useful for a calculator. It omits assumptions such as whether thickness must be in SI meters versus the schema's mm.

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 sentences covering formula, use case, inputs, output, and a sibling pointer — front-loaded with the formula and with no filler. Nothing here is redundant with the schema or title.

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?

An output schema exists so return values need no further explanation, and annotations cover the safety profile. The remaining gaps are the mm-vs-m unit confusion and the failure to disambiguate from calculate_insulation_r_value.

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%, so both parameters are already documented as thickness_mm (mm) and lambda (W/m·K). The description instead says 'thickness m', which conflicts with the schema's millimeter unit and would make the stated formula R = thickness/lambda numerically wrong if followed literally.

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 precise verb+resource with the underlying formula (R = thickness/lambda), so the operation is unambiguous. It does not, however, distinguish itself from the near-identical sibling calculate_insulation_r_value, leaving an agent to guess which of the two to call.

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 a clear domain context ('use for insulation specification (RT2020/RE2020)') and routes to list_bundles for related construction calculators. It offers no when-not guidance and never mentions the overlapping insulation sibling, so exclusion criteria are absent.

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