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

readOnlyHint=true already covers the safety profile, but the description adds real context beyond annotations: the lookup is exact-match and single-record, and it enumerates the returned sections (basic info, addresses, taxonomies, identifiers, other names). It does not mention error behavior for a non-existent NPI.

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?

Three short sentences, purpose front-loaded, then return contents, then source API. No filler and nothing repeated from the title.

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 one-parameter read-only lookup with no output schema, the description adequately sets expectations about what comes back. Only minor gaps remain (behavior on a missing or invalid NPI), which are not blocking 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 description coverage is 100% and the single parameter already documents the 10-digit format and an example. The description only echoes 'exact 10-digit', adding no syntax or edge-case meaning beyond the schema, so the baseline 3 applies.

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 verb ('look up'), resource ('healthcare provider'), and the exact discriminator ('exact 10-digit NPI'), plus what the record contains. The contrast with the sibling search tools is implicit via 'single' and 'exact' rather than explicit, so it stops short of naming an alternative.

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: this is the tool for when you already hold a known NPI, versus the nppes_search* siblings for finding one. It never states that condition or names the alternatives, so the agent must infer the routing rule.

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