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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful behavioral context beyond them: the chart contains an LPI sweep with alignment marks and must be printed at 100% scale then physically evaluated with the lens sheet. It doesn't describe output file format or return shape, but for a deterministic read-only generator this is strong.

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 sentences, front-loaded with the purpose, then usage conditions, then the routing exclusion. No sentence is redundant and the most decision-relevant information (what it produces and the alternative) comes first.

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?

No output schema exists, but the description compensates by describing what the chart contains and how it is meant to be consumed. Required inputs, defaults and the alternative tool are all covered, leaving nothing an agent needs missing.

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 100%, so every parameter including lpi, steps, resolution, widthIn and heightIn is already documented in the schema. The description adds no parameter syntax or format detail beyond it, so the baseline 3 applies.

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 artifact ('Generate a printable LPI pitch-test chart') plus the exact situation it serves ('measure or calibrate the actual lens pitch'). It explicitly distinguishes itself from the sibling calculate_output_params, so an agent can route correctly without opening either 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 concrete positive triggers ('has a nominal LPI but wants to verify the real LPI, calibrate a new lens sheet... before interlacing') and an explicit exclusion with a named alternative ('Do not use this tool merely to calculate print resolution... use calculate_output_params'). Both when-to-use and when-not-to-use are covered.

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