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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds real value by disclosing the returned fields and clarifying that a null guideline means the record rests on primary literature, giving the agent a way to interpret output it would otherwise misread.

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?

A single dense sentence with the resource stated first, the optional-parameter behavior second, and the enumeration of returned fields nested in the middle. No filler and nothing repeated from the schema.

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?

With no output schema, the description carries the burden of describing return values, and it does so (guideline, recommendation summary, phenotypes, sources). Combined with 100% parameter coverage and full annotations, an agent has everything needed to call and interpret the result.

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 is 3, but the description goes beyond the schema by explaining the consequence of omitting drug (enumerate all curated drugs) and by defining one of the guideline values as null. That adds interpretive meaning the parameter descriptions do not contain.

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?

Names a specific resource (pharmacogenomic guidance) and scope (one gene, optionally one drug), and enumerates what the record contains (guideline, recommendation summary, phenotypes, sources). It does not explicitly differentiate itself from siblings like lookup_gene or check_medications, so it stops short of a 5.

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 clause 'Omit drug to list every drug curated for that gene' tells the agent exactly how to choose between the two usage modes. There are no explicit exclusions or named alternatives among siblings, which keeps it at 4 rather than 5.

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