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

Annotations already cover the safety profile (readOnly, idempotent, not open-world), and the description adds substantial context beyond them: normalization with a residual flag, snapshot date in every answer, data sources with license, the decision-support disclaimer, the transplant ambiguity caveat, and the summary.actionable derivation. This is unusually rich behavioral disclosure.

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 purpose and then the return shape, with the disclaimers and transplant caveat last. It is dense and long, with mild redundancy between the 'decision support only' line and 'decides nothing', but nearly every sentence carries distinguishing information.

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 tool of this complexity, with nested objects and an output schema present, the description is complete: sources, snapshot freshness, normalization behavior, per-allele return contents, and the actionable summary are all covered, so an agent knows what it gets and when it applies.

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 baseline is 3, but the description adds value by explaining input tolerance: any era or shorthand works (A*3101, B*5701, HLA-B*15:02:01G) and every conversion leaves a flag. It reinforces the alleles-vs-typing choice already in the schema rather than adding new syntax detail.

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?

Opens with a specific verb+resource: 'Which drugs an HLA typing carries a published pharmacogenomic association for.' An agent can distinguish this from siblings like allele_info, pgx_pair, and normalize_allele because the description explicitly says it normalizes internally and is keyed by two-field HLA allele for drug associations.

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?

Provides clear use context (CPIC/PharmGKB drug-association lookup for an HLA typing, decision support only) and constraints (allele strings only, no patient identifiers). It does not explicitly name alternatives such as normalize_allele or pgx_pair, but by stating normalization is handled internally it implicitly routes the agent away from those.

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