engineering.capacitor_combine

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

Annotations already declare readOnly/idempotent/closed-world, so the description's job is to add computation semantics — and it does: 50-significant-digit Decimal arithmetic, output unit identical to input unit, and input validity constraints (positive, at least one). It does not discuss behavior on invalid input or mixed-unit inputs, which would have completed the picture.

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?

Four compact sentences: purpose first, formulas second, input/output contract third, misuse caveat last. No filler, and the highest-value information (what it computes) 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 two-parameter read-only calculation with an output schema, everything an agent needs — accepted topology values, input format, unit contract, precision — is stated. Return-value shape can be left to the output schema.

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 0% and topology is an unconstrained string with no enum, yet the description supplies the full allowed value set ('series'/'parallel') with the formula each triggers. It also specifies the capacitors element type and format (Decimal strings in farads, strictly positive, minimum one element) and the unit of the result — fully compensating for the bare schema.

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 verb+resource (combined capacitance of multiple capacitors) and immediately gives the exact formula for both topologies, so the agent knows precisely what quantity is returned. The closing caution that resistors and inductors use the inverse series/parallel convention indirectly distinguishes this tool from engineering.resistor_series, engineering.resistor_parallel, and engineering.inductor_combine.

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 topology semantics make the two usage modes explicit, and the misuse warning effectively steers the agent away from applying these formulas to resistor/inductor problems. It stops short of naming the alternative sibling tools directly (e.g. 'for resistors use engineering.resistor_series'), so it is clear context rather than a full routing rule.

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