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

The annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so the safety profile is covered. The description adds useful detail about the breadth of content, including variants, phenotypes, and array limitations, but does not disclose edge-case behavior such as handling of unknown gene symbols or response formatting. This adds moderate value beyond the annotations.

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?

The description is a single, well-structured sentence that front-loads the core idea ('Everything curated about one gene') and then uses a colon-delimited list to enumerate specific content categories. There is no filler or redundant wording, and every segment contributes useful 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 simple read-only, one-parameter lookup with no output schema, the description gives a solid account of what the agent can expect in the response, including a notable nuance about consumer genotyping array limitations. It does not mention invalid-symbol behavior or explicitly contrast with sibling tools, but these are minor gaps given the straightforward schema and sibling names.

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?

The only parameter, 'symbol', is fully documented in the schema with an example ('CYP2C19') and case-insensitivity. The description adds no additional meaning about the parameter, so the schema carries the full burden. This matches the baseline for high schema coverage.

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 clearly specifies the tool's purpose: retrieving curated information about one gene, and enumerates content types (function, variants, phenotypes, drug interactions, array limitations, sources). It focuses on a single gene, which distinguishes it from siblings like list_genes and lookup_variant, but it does not explicitly name those siblings or state how it differs from 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 description implies the tool should be used when an agent needs comprehensive gene-centric curated data. However, it does not explicitly state when to choose this over lookup_variant or lookup_drug_gene, nor does it provide any exclusions or alternative routing. The agent must infer usage from the tool name and sibling context rather than from explicit guidance.

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