engineering.moody_friction_factor

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

Annotations already cover read-only/idempotent/closed-world safety, and the description adds substantial behavior beyond them: Swamee-Jain seeding, 100-iteration cap, 1e-10 tolerance, immediate laminar return with iterations 0, an explicit error mode on non-convergence, and 30-significant-digit output precision. No contradictions with 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?

A single dense paragraph, front-loaded with the equation and solution method, then edge cases and precision. Appropriate length for a numerical solver; the embedded equation is informative rather than filler, though the prose is somewhat packed.

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?

An output schema exists so return format needn't be explained, and annotations cover safety; the description covers method, regime handling, units, error behavior and precision. The one substantive gap is the string-typed numeric inputs, whose expected format (arbitrary-precision decimal strings) is left implicit.

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% (three bare string-typed parameters), so the description must compensate and largely does: reynolds declared dimensionless, roughness and diameter required to share a length unit. It stops short of stating that the parameters are numeric strings / decimal format, which matters given the string typing.

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: iteratively solving the Colebrook equation to obtain the Darcy friction factor f, with the governing equation written out. This is distinguishable from siblings like engineering.darcy_weisbach (which consumes f) or engineering.fluid_reynolds (which produces Re) without opening any schema.

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 domain-level guidance: Re < 2300 short-circuits to f = 64/Re, turbulent regime uses iteration, and convergence failure raises an error. However, it never routes the agent among alternatives (e.g. darcy_weisbach, hazen_williams_flow) or states when this tool is the wrong choice, leaving usage implied by the input triad.

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