engineering.darcy_weisbach

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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint=false, so safety is covered; the description adds genuine extra context: no rounding, 50 significant digits of precision, and the exclusion of minor/local losses. It does not describe output shape or any numeric-range limits, which keeps it just short of a 5.

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?

Three dense sentences, front-loaded with the formula and result units, followed by parameter semantics, then the sibling hand-off and scope exclusion. No filler or repetition of the parameter list.

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 six-parameter formula tool with an output schema present (so return values need not be explained), the description covers the equation, unit conventions, defaults, precision policy, scope limits and prerequisite sibling. Nothing an agent needs in order to call 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 description coverage is 0% (only bare titles), so the description carries the full burden and does it: friction_factor is dimensionless, length and diameter in m, velocity in m/s, density defaults to 1000 kg/m³, gravity to 9.80665. Every one of the six parameters gets meaning or units beyond the schema's titles.

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?

The description gives a specific verb and resource (Darcy-Weisbach friction head loss and pressure drop) plus the exact formulas h_f = f·(L/D)·v²/(2g) and Δp = ρ·g·h_f, so the agent knows precisely what is computed. It also distinguishes itself from the sibling engineering.moody_friction_factor, which supplies the friction factor rather than the loss.

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?

It explicitly routes the agent: if the friction factor is unknown, call moody_friction_factor first. It also states a negative scope condition — local losses from valves or bends are not included — which is exactly the when-not guidance an agent needs to avoid misusing this tool for fitting losses.

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