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

Annotations already establish a safe, read-only, idempotent operation, and the description adds substantial behavioral context beyond them: exact answer semantics, included evidence, the drug-only plan case, freshness caveats, and a cost signal. The not_found warning is especially important for preventing misuse.

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?

The description is front-loaded, dense but well organized, and every sentence carries useful information about answer handling, evidence, caveats, or cost. There is no repetition of schema or annotation data.

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?

Even though an output schema exists, the description adds necessary semantic interpretation of the answer values that an agent must know. It covers the provider-not-found caveat, the no_provider_network case, evidence fields, and directory freshness, making the tool complete for correct invocation and reporting.

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?

The input schema has 100% description coverage and fully explains npi, plan_id formats, and the optional year default. The description does not add meaning beyond the schema for these parameters, so the baseline of 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 first sentence states a precise verb and resource: whether one plan's network directory lists one provider. It is clearly distinct from the batch sibling and other lookup tools by emphasizing the single-provider/single-plan scope.

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?

The description gives strong interpretation guidance for each answer, including the critical warning not to treat not_found as out-of-network. However, it does not explicitly name alternatives such as check_network_batch for multiple providers, leaving that routing to the sibling name alone.

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