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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful boundaries beyond that: it operates only on notation, does not alter the actual prescription, and explicitly excludes diagnosis or prescription generation. This is useful context for safe invocation.

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 compact sentences with zero filler. The core operation is front-loaded, and the scope limitations are stated efficiently. Every sentence earns its place.

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 pure calculation tool, the description covers the operation, key units, axis bounds, and scope exclusions. With no output schema present, it could ideally say more about the returned form or the effect of the language parameter, but the tool is simple enough that an agent can correctly invoke it from this definition.

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 must compensate. It does add semantic value by specifying dioptres and degrees and the axis range, but it does not explain the language parameter or clarify the role each parameter plays in the transposition. Parameter names are reasonably self-explanatory, but the compensation is only partial.

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 names a specific verb ('Transpose'), a precise resource ('sphere/cylinder notation'), and the key invariant ('without changing the prescription'). It is clearly distinguishable from the sibling calculation tools and knowledge lookups, even without naming them.

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 intended use is implied by the operation itself, and 'Does not diagnose or generate prescriptions' provides a negative boundary. However, it does not explicitly say when to choose this over calculate_decentration or calculate_prism, nor does it offer an alternative-tool pointer.

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