engineering.mech_strain

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

Annotations already declare readOnly/idempotent/closed-world, so the bar is lower; the description still adds behavior the annotations can't convey: no rounding, 50 significant digits, and acceptance of negative (compressive) inputs. It does not state the error case for original_length = 0 or the return shape.

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 tight sentences, formula and purpose first, then the unit/range constraints, then the precision rule — no 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?

With an output schema present the description needn't explain return values, and it covers the edge cases that matter for a strain calculation. The 50-digit precision statement is a good signal; missing only an explicit note on invalid zero-length input.

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% with only bare names, so the description must compensate; it explains that both arguments are lengths requiring a common unit and gives the valid range/sign of each. It leaves out that both are passed as decimal strings, which the schema type hints at but never documents.

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 plus the exact formula (ε = ΔL / L, dimensionless), which pins the tool's scope and separates it from engineering.thermal_expansion_strain and engineering.mech_stress without needing 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 real preconditions for correct use — both lengths in the same unit, original_length > 0, delta_length may be negative for contraction — but never names an alternative tool or says when to pick this over a sibling.

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