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

Annotations already establish read-only, idempotent, and non-destructive behavior. The description adds valuable behavioral context beyond annotations: unknown slugs produce a stable not-found result, and the educational response excludes diagnosis and private data. No contradiction with annotations exists.

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 two sentences with no filler. The first sentence states the core purpose and scope, and the second covers important edge-case behavior and content restrictions. Every phrase earns its place.

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 single-parameter, read-only lookup with an output schema and strong annotations, the description covers the key operational behaviors: exact slug matching, unknown-slug handling, and response-level privacy exclusions. It falls just short of full completeness by not providing any guidance on when to prefer this tool over sibling lookup/search tools.

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 input schema fully documents the slug parameter with meaning, length constraints, and example values, so the description does not need to add much. The description reinforces that the slug must be an exact public category slug and mentions unknown-slug behavior, which is helpful but does not significantly extend the schema's semantic 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 states that the tool returns biomarkers for one exact public category slug, using a specific verb and resource. It is easily distinguished from sibling tools like list_biomarker_categories (which returns categories) and get_biomarker/get_biomarkers (which deal with individual or multiple biomarkers).

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 does not say when to use this tool versus alternatives such as list_biomarker_categories or search_biomarkers. The phrasing 'exact public category slug' implies the caller should already know the slug, but no explicit when-to-use or when-not-to-use guidance is provided.

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