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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered without the description. The description adds the Hazen-Williams method name, which tells the agent the physical assumptions in play, but omits any statement that it is water-specific or what validity ranges apply.

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?

Two short sentences, front-loaded with the core action, which is efficient. However, 'Returns: {C_coefficient}' is an unresolved template placeholder that reads as a leaked artifact rather than meaningful prose, and it duplicates what the output schema already covers.

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 values need not be explained, and the 100%-covered input schema carries parameter detail. The description supplies the method name, which is the main piece of context an agent needs to trust the result; only applicability limits (water-only, valid diameter/pressure ranges) are 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 100%, so all four parameters (length_m, material, diameter_mm, pressure_bar with default) are already documented, including the note that material affects the Hazen-Williams C coefficient. The description adds nothing beyond that, so the baseline of 3 applies.

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 states a specific verb (calculate) and resource (water flow rate through a pipe) and names the governing method (Hazen-Williams), so the agent knows exactly what computation is performed. It does not, however, distinguish this from near-neighbors like calculate_pipe_diameter, calculate_flow_rate_convert, or calculate_water_pressure_loss; the pointer to list_bundles is a bundle hint, not sibling differentiation.

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?

There is no when-to-use guidance, no statement of prerequisites, and no routing between this tool and the many overlapping flow/hydraulic calculators in the sibling list. 'See list_bundles for related plomberie calculators' gestures at a bundle but gives no selection criteria.

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