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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, yet the description still adds a concrete inventory of return contents — row count, source last-updated, latest approval date, licence, fields present/absent, distinct values with counts. That is above what the annotations provide, though it says nothing about freshness guarantees or response size.

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?

One dense sentence that front-loads the resource and then lists outputs; every clause maps to a returned field. It is long, but the closing 'use it for...' directive comes last rather than first, costing a little front-loading.

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 must define the return shape itself, and it does so exhaustively (counts, dates, licence, present/absent fields, distinct values). Nothing an agent needs to call this correctly is missing.

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 tool takes zero parameters, so per the rubric the baseline is 4. The description's reference to 'filter spellings' implies callers will reuse its output as filter inputs elsewhere, which is useful framing but not parameter semantics for this tool.

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 resource (HSA registered therapeutic products listing) and enumerates exactly what metadata it returns, then contrasts itself with the sibling hsa_sg_search. An agent can tell it apart from other hsa_sg_* tools 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?

Explicitly instructs when to use it ('for exact filter spellings before hsa_sg_search') and names the downstream alternative. It gives clear positive context but no exclusion cases or prerequisites.

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