cfd_pipe_flow

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

With no annotations, the description carries the full burden and does well: it discloses that results are analytic (no solver), that laminar Hagen–Poiseuille is exact with D⁴ scaling, that turbulent is a ±10% Moody-band correlation with labeled fidelity, and that a Colebrook value is always reported for turbulent flow. It does not address input-validation behavior (e.g., what happens if both flow_rate_lpm and velocity_m_s are supplied, or if inputs are non-physical), so it falls short of a full behavioral contract.

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?

Every clause is substantive and the defining constraint ('NO solver') is front-loaded in the first line. It is dense and parenthetical-heavy, which makes it slightly harder to scan than it needs to be, but there is little filler.

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 an 8-parameter analytic tool with no output schema, the description enumerates the returned fields (reynolds, regime, friction_factor, colebrook_friction_factor, pressure_drop_pa, wall_shear_pa, hagen_poiseuille_pa, laminar, fidelity, band_pct, escalate_to), the fluid input model, the regime logic, and the escalation path. Nothing an agent needs in order to call it correctly is absent.

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%, so the description must compensate, and it largely does: it clarifies that flow is supplied as either `flow_rate_lpm` or `velocity_m_s`, that fluid properties come from a named `fluid` ('water-20c','air-20c','oil-sae30-20c','glycerin-20c') or an explicit `mu_pa_s`+`rho_kg_m3` override, and that `roughness_mm` switches the turbulent model to Colebrook–White. What it does not resolve is precedence when both flow inputs are given, or that diameter_mm/length_mm are the required pair.

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 and resource ('analytic straight-pipe pressure drop') and immediately distinguishes itself from the solver sibling by declaring '(NO solver)' and calling itself 'the fast internal-flow screen and the exact gate the OpenFOAM cfd_internal_flow solve is checked against'. An agent can tell it apart from cfd_internal_flow_submit without opening the 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?

Gives explicit routing: it is the fast analytic screen, and 'Escalate turbulent cases to cfd_internal_flow_submit(turbulence=\'kOmegaSST\')'. It also names the exact conditions under which it applies (laminar vs turbulent, with/without roughness). No inference required.

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