PCB Trace Width for Current (IPC-2221)

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

Annotations already declare safe, read-only, idempotent behavior. The description adds value by explaining the non-linear nature of the calculation, the structured return format, and the formula parameters, enhancing transparency beyond annotations.

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?

Extremely concise: includes formula, args, returns, and an example in a few sentences. No redundant information.

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 4 parameters, high schema coverage, and output schema present, the description is complete. It covers purpose, formula, parameter details, example, and a caution about non-linearity.

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 covers 100% of parameters, but the description adds meaning by explaining the layer types, default values, and the physical meaning of copper_oz. The example clarifies parameter effects.

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?

Clearly states it calculates minimum trace width for current per IPC-2221. Includes the governing formula and distinguishes itself from sibling calculators (e.g., microstrip impedance, resistor code) by its specific purpose.

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?

Provides explicit usage: 'Do not guess trace widths'. Gives an example and notes that internal layers need ~2x width. While it doesn't explicitly list when not to use, the sibling list implies alternatives, and the context is clear.

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