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

With no annotations, the description must disclose behavior. It clarifies that the tool returns an object with specific keys (lambda, r_value, etc.) and implies it is a read-only calculation. It does not mention side effects or permissions, but for a calculator this is sufficient transparency.

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?

The description is extremely concise: two sentences giving the formula, comparison target, and return structure. No unnecessary words, and information is front-loaded.

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 simple two-parameter calculator, the description covers the formula, purpose, and output fields. However, it does not mention edge cases like very small thickness/lambda values or what happens if inputs are invalid, but these are partly handled by schema constraints. Overall, it is adequate for its complexity.

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?

The schema already provides full descriptions for both parameters (thickness_mm and lambda), including example values for lambda. The description adds no extra parameter context beyond what the schema offers, so it meets the baseline for 100% schema coverage.

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 clearly states the tool calculates thermal R-value using the formula R = thickness/lambda and compares with RE2020 targets. It also lists the return object keys, making its purpose very specific. However, it does not explicitly differentiate from sibling calculators beyond a reference to list_bundles.

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?

The description gives the formula and mentions comparison with targets, but provides no explicit guidance on when to use this tool versus alternatives. It only weakly references 'See list_bundles for related calculators', leaving the agent to infer usage context.

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