Get System Units

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

No annotations are provided, so the description carries the full behavioral burden, and it discloses almost nothing beyond the name. It does not say whether the call is a pure read, what happens if no system is open, or what unit values can come back — the 'current' qualifier is the only added context.

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?

One short, front-loaded sentence with no filler or repetition. It is efficient, though the extreme brevity is part of why behavioral detail is absent rather than a virtue of tight writing.

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 a zero-parameter getter this is close to adequate, but with no output schema the description should indicate what is returned (unit options such as mm/inches) or any precondition such as an open system file. As written, the agent must discover the return semantics by calling it.

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?

The tool takes zero parameters, so per the rubric the baseline is 4. The description correctly implies a no-argument getter scoped to the active system, and there is nothing parameter-related to compensate for.

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 ('Get') and resource ('the current optical system's lens units'), so the agent knows exactly what is retrieved. It is distinguishable from zemax_set_system_units by the verb, but it does not explicitly name or contrast with that sibling or with zemax_get_mtf_units.

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?

Usage is only implied: read the lens units of the currently open system. There is no statement of when to prefer this over zemax_get_mtf_units or any prerequisite (e.g., a file must be loaded), leaving the agent to infer context.

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