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

Beyond readOnlyHint/openWorldHint, it discloses the upstream source (CMS NPPES), the entity-type restriction, and a full payment model: $0.002 USDC per successful call via x402 on Base/Solana/Arc with failed calls uncharged. Cost and billing behavior are exactly what an agent needs before calling a paid tool.

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 tight sentences: the first front-loads what data is returned and the search keys, the second carries the pricing/constraint payload. No filler and no repetition of the schema.

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 an output schema present, the description needn't define return values, and it still previews the key fields. The NPI-1 restriction, the required search keys, and the full x402 pricing model cover everything an agent needs to decide and invoke correctly.

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 description coverage is 100%, so lastName, state and limit are already documented. The description adds only the composite framing that the search is by last name plus state, which is minor incremental context rather than new semantics — baseline 3 is appropriate.

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 names a specific verb and resource: NPI records from the CMS NPPES NPI Registry, searched by last name and 2-letter state, with the exact fields returned. It never names a sibling (e.g. b2b_doximity or b2b_webmd_healthcare_provider_directory) that an agent should prefer or avoid, so sibling differentiation is left to inference.

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 states the required search axes (last name plus 2-letter state) and an explicit exclusion — 'Individual providers (NPI-1) only' — so the agent knows organizational NPIs are out of scope. No alternative directory tool is named for when this lookup is the wrong fit.

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