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

Annotations already establish readOnlyHint=true and openWorldHint=true. The description adds useful non-annotation context: pricing without an API key is $0.05 USDC per successful call via x402 on Base or Solana, which matters for invocation cost and authentication expectations.

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 compact sentences front-load the resource and identifiers, then append critical payment context. There is no redundant or filler language.

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 one-parameter lookup with no output schema, the description lists the key return fields and explains payment context. It could additionally clarify ambiguity or multiple-match behavior, but it is largely complete for correct invocation.

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 the single query parameter is fully documented in the schema, including accepted formats. The description is consistent but mostly repeats that queries may be by NPI or name rather than adding syntax beyond the schema.

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 concretely states the resource (US healthcare providers), the lookup keys (NPI number or name), and the returned data (provider type, specialties, licences, addresses, phone numbers). This clearly separates it from siblings like us_company_lookup or phone_lookup.

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?

It implies when to use the tool by naming acceptable query inputs, NPI number or provider/organisation name, but it does not explicitly compare against alternatives or state when not to use it. The guidance is adequate but leaves routing to inference.

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