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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, closed-world, so the safety profile is covered. The description adds real behavioral context the annotations cannot: the table's ambient/conductor-count assumptions and the fact that adjustment, correction, and 240.4(D) limits are NOT applied — a misuse guard. It stops short of noting table/edition or lookup failure behavior.

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 engineered sentence with the subject (allowable ampacity) front-loaded and all caveats compactly following. No filler sentences. It is dense to the point of being parenthesis-heavy, which slightly hurts scanability, but nothing is wasted.

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?

Given an output schema exists and annotations cover the safety traits, the description supplies the missing piece: the validity envelope of the lookup value. What is missing is only routing guidance among the nine siblings. For a deterministic table lookup, that is a minor rather than a blocking gap.

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% and every parameter is an enum with its own explanation (AWG/kcmil forms for size, 60/75/90 column guidance for temp, cu/al for material). The description adds no parameter-level meaning beyond what the schema already provides, so the baseline 3 applies.

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 a specific verb+resource (allowable ampacity of one insulated conductor) and pins the exact source table (NEC 310.16) plus its scope conditions. It also implicitly distinguishes itself from sizing siblings like wire_size by stating the value is 'before any adjustment or correction factors and before the 240.4(D) small-conductor limits.' An agent can tell exactly what quantity is returned.

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 scope qualifiers (≤3 current-carrying conductors, 30°C ambient, no adjustment/correction factors) tell the agent when the returned value is valid, which is genuinely useful. However, it never states when to prefer this tool over siblings such as wire_size or voltage_drop, nor any exclusions. Usage is implied rather than directed.

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