science.thin_lens

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

Beyond the read-only and idempotent annotations, the description adds meaningful behavioral detail: no rounding is performed, invalid combinations such as zero distance or infinity raise errors, and real versus virtual images follow a positive/negative distance sign convention. This is exactly the kind of operational context an agent needs before invoking the tool.

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?

The description is compact and front-loaded: it states the equation and output first, then input rules, error conditions, and sign convention. Every sentence adds necessary information with 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?

Given three parameters, an existing output schema, and the mathematical nature of the tool, the description is complete enough to call correctly. It covers input cardinality, types, units, error cases, sign convention, and the additional magnification return value without redundantly describing output structure.

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 carries the full burden and compensates well. It explains that focal_length, object_dist, and image_dist are Decimal strings, that exactly two must be supplied, that units must be consistent, and how signs encode real versus virtual images.

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 calculation: solve the thin lens equation 1/f = 1/p + 1/q for exactly one missing value and return magnification m = -q/p. It names the three possible quantities and their roles, so an agent can immediately distinguish this from unrelated science tools such as science.snell_law or science.bragg.

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 gives clear invocation rules: supply exactly two of the three values as Decimal strings, keep length units consistent, and note that zero distance or infinity/parallel-ray combinations are errors. It does not name an alternative tool, but there is no obvious sibling alternative, so the remaining gap is minor.

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