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

Annotations already cover the read-only/idempotent/closed-world profile, so the description's marginal value is in disclosing output content — fill percentage, jam ratio for three conductors, per-conductor area with its table, and named gaps in a table — plus the 'deterministic, no LLM' guarantee. That is meaningful behavior beyond structured fields.

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 dense sentence, front-loaded with the subject and scope, and every clause carries information (tables, percentages, jam ratio, defect reporting). The nested parentheticals and the '...' raceway ellipsis make it slightly harder to scan than it could be.

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?

No output schema exists, and the description compensates by stating what the result contains (fill, jam ratio, areas with their table, missing rows). Combined with full schema coverage and annotations, little an agent needs to invoke it correctly is missing.

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 parameters are already documented. The description still adds real semantics not in the schema: the 53/31/40% Table 1 limits, the 60% nipple exception, and that a cable may be supplied by diameter — clarifying how inputs map to the calculation.

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?

Names a specific computation — the smallest raceway trade size that holds a given conductor list — and scopes it to NEC Chapter 9 fill. An agent can distinguish it from tray_fill (cable tray) and pull_cable (installation), and it names the governing tables (1, 5, 5A, 8).

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 domain context (conduit fill sizing) implies when to call it, and the nipple flag hints at a branch condition, but there is no explicit statement of when to prefer this over siblings like tray_fill or design_cable, and no prerequisites or exclusions are given.

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