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

Beyond the readOnly/idempotent/closed-world annotations it discloses source tables (NEC Ch. 9 Table 8, UL 1581 Table 30.3, IEC 60228:2004 Table 2), the 400 error behavior for unknown sizes, determinism/no-LLM, and the caveat that an ICEA K cannot be verified against an IEC Ki. It does not say what happens if both awg and mm2 are supplied, or neither, which is the one behavioral gap.

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?

Front-loaded with the conversion scope, then inputs, then alternatives, then behavior — a sensible order with no filler sentences. It is written as a long semicolon-chained block, and the source-table parenthetical is dense, which costs a point on readability but not on content value.

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 5-parameter, zero-required, no-output-schema conversion tool it covers inputs, defaults, error behavior, sources, and sibling routing. What is only partially covered is the return shape — 'each size with its resistance and source' hints at a table but the granularity for a single-size lookup versus a full list is not spelled out.

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 the baseline is 3, but the description adds real meaning: awg and mm2 are mutually exclusive alternatives rather than independent filters, metal defaults to Cu, and k is specifically the ICEA constant expressed in MΩ·km with a stated comparability limitation. That goes beyond the schema's one-line property descriptions.

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 transformation: AWG/kcmil ↔ IEC 60228 mm², in both directions, by area and by maximum resistance at 20 °C. It also names the two sibling tools it is not (decode_cable_code for whole designations, design_cable for sizing), so an agent can route without opening a schema.

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?

Explicit routing: 'Use it to translate a North American size; to decode a whole designation use decode_cable_code, to size a cable design_cable.' It also states the input rule 'Send awg or mm2 (one of them)' and the metal default, so when-to-use and which-argument-to-supply are both covered.

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