create_lens

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

With no annotations, the description carries the full burden and does disclose real behavior: it publishes a verified recovery point (a side effect), requires an empty session, and explains that with image_solve='pim' the surface thickness becomes CODE V-derived and no longer directly editable. It omits permission/error behavior, but the non-obvious mutation semantics are well covered.

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 sentences, front-loaded with the core action and precondition, then the image_solve caveat. Every sentence carries information, though the PIM explanation is slightly dense.

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 no explanation. The description covers the key non-obvious aspects (empty-session requirement, recovery point, PIM behavior); remaining gaps like units handling and aperture kinds are documented in the nested schema.

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?

Top-level schema coverage is reported as 0%, and the description compensates richly for exactly one field (image_solve='pim' and its non-editable consequence). The many nested fields (units, aperture_kind, wavelengths, fields, surfaces) rely entirely on their nested schema descriptions and get no extra meaning from the description.

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: creates a new single-zoom lens from restricted spherical specs. The 'in an empty session' qualifier and the 'typed values only' framing help distinguish it from open_lens/update_lens, though no sibling is named explicitly.

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?

The 'empty session' precondition is a useful usage constraint, but the description never states when to prefer create_lens over open_lens or edit_lens_structure, nor any explicit exclusion. Usage is implied by session state rather than spelled out.

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