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

With no annotations at all, the description must carry full behavioral weight. It does well on the non-obvious mechanics: distance is computed between ZIP code centres, results are capped at 12, and the NPI path implicitly excludes the source provider ("who else"). It says nothing about result ordering, what happens when a provider's specialty or ZIP is missing, or what data comes back, which are real gaps for an unannotated 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?

Three sentences, front-loaded with the triggering use case, then the semantics, then the cap. Every clause carries information; nothing is padding.

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 four-parameter, annotation-free tool with no output schema, the description covers purpose, both input modes, and the distance basis. It leaves unclear what fields are returned per provider and how partial/degenerate inputs (unknown NPI, unmatched ZIP) are handled, so an agent can select the tool but not fully predict its behavior.

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 75%, so the baseline is 3; the description earns a bump by explaining the relationship the schema only hints at — npi supplies both specialty and ZIP automatically, while the zip path requires an accompanying taxonomy, and distance is measured between ZIP centroids.

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 the specific resource (providers sharing a specialty) and the specific relationship (nearest to a given NPI or to a ZIP+taxonomy, measured by ZIP-centroid distance), plus the 12-result cap. That is enough to distinguish it from search_providers or lookup_provider on intent, though no sibling is named 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?

"Use when the question is who else does this nearby, or for alternatives to a provider" gives a concrete triggering question type. It lacks an explicit exclusion (e.g. don't use for keyword/name search — use search_providers), so the routing is clear but not airtight.

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