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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds real behavioral context beyond them: partial-input behavior ('Missing axes or faces may lower the ceiling'), the BGS-both-axes rule, and the framing constraint ('never describe it as a predicted grade'). These caveats meaningfully guide correct interpretation.

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?

Front-loaded with the core purpose, then usage, then caveats. Sentences are dense but each carries distinct information (input formats, requirements, output framing). Slightly packed but no wasted clauses.

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-value detail needn't be spelled out, yet the description still notes provenance, limiting face/axis, and distance to the next step. Input requirements and caveats are covered, making it complete for a multi-provider grading tool.

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 coverage is 100%, so the baseline would be 3, but the description adds semantics the schema lacks: it accepts reversed ratios and requires 'at least one axis' even though the schema marks zero required parameters. That requirement and reverse-order acceptance are genuinely new information.

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+resource ('Convert known card centering ratios into the maximum grade') across four named grading companies. The phrase 'without needing a photo' implicitly distinguishes it from the sibling measure_card_centering, letting an agent route correctly without opening a 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 a concrete usage trigger ('questions such as "is 58/42 a PSA 10?"') and states input constraints ('At least one axis is required'). It does not explicitly name the alternatives (get_centering_standards, measure_card_centering) or state when-not to use it, so it falls short of full alternative routing.

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