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

Goes well beyond the readOnly/idempotent annotations: says results are exact rationals, that extra supplied values are verified rather than ignored, enumerates the degenerate cases that error, and discloses cost ($0.001 USDC per successful call via x402 on Solana) plus an equivalent HTTPS endpoint. Nothing about calling behavior is left to guess.

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 core relation and the input contract, then edges cases, then pricing. Dense but every clause is functional; the pricing and HTTPS endpoint lines are operational metadata rather than computation semantics, which slightly dilutes focus.

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?

With no output schema and no annotation detail, the description still tells the agent what comes back (the two missing quantities as exact rationals), what fails and why, and what a call costs — everything needed to invoke it correctly and interpret the result.

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 0% — the four parameters are bare strings with only maxLength — so the description must carry the load, and it does attach units to each name (volts, amperes, ohms, watts) and states that exactly two are required. It omits the accepted string format (decimals vs. fractions, exponent or prefix notation), which leaves a real ambiguity for a tool returning exact rationals.

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 physical relation and scope: "Ohm's law for one passive resistor," with the operation spelled out (supply any two of V/I/R/P, get the other two back). The phrase "one passive resistor" implicitly separates it from resistor_network and voltage_divider, but no sibling is named explicitly.

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?

Gives a clear calling contract — provide any two of the four quantities — plus explicit rejection conditions (three or four values checked and rejected on disagreement, zero-ohm and zero-current cases rejected). It never names an alternative tool or a when-not-to-use-this case, so it stops short of a 5.

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