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

Annotations already declare readOnlyHint and openWorldHint, so the description's added value is the US-only scope of payers and the disclosure that each answer carries its criteria and the payer policy document it derives from. The "reference information, never a guarantee" caveat is a real behavioral constraint an agent needs when reporting results.

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?

Two short sentences with no filler: what it answers plus provenance first, the reliability caveat second. Front-loaded and fully earning its length.

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 usefully previews the response contents (criteria plus the source policy document) and sets expectations about reliability. It could say more about how definitive or granular the answer is (e.g., plan-level variation, step therapy), but it covers what an agent needs to call and report it.

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% and both parameters have examples, so the schema carries the parameter meaning. The description only adds the constraint that the payer must be a US insurer, which is useful but minor; it adds no naming, formatting, or matching guidance beyond the examples.

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?

"Whether a named US insurer covers a named GLP-1" states the exact question answered and the two inputs, and adds that the answer includes criteria and the source payer policy document. It is clearly distinct from price-oriented siblings (get_price, cheapest, fair_price), though it doesn't name them explicitly.

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?

Usage is implied rather than stated: it is a reference lookup for payer/drug coverage questions, and the caveat "never a guarantee of coverage" signals how the output should be treated. No when-not-to-use guidance and no pointer to the price/program siblings for cost questions.

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