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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description need not restate safety. It adds value by disclosing the return field set (labeler name, brand name, generic name, etc.) and the FEI linkage caveat, which informs expected behavior. It does not mention pagination quirks or rate limits, but these are largely covered by the schema and annotations.

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 three sentences, each earning its place: the first states the action and search keys, the second lists return fields, and the third provides a critical caveat and related-tool pointers. It is front-loaded with the primary purpose and contains no redundant phrasing.

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?

Despite lacking an output schema, the description enumerates the return fields clearly and provides usage context (e.g., the FEI caveat) and tool differentiation. It covers the essential information an agent needs to select and invoke the tool correctly, including related tools for adjacent use cases.

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% coverage, with each parameter having a descriptive name and a short description. The tool description does not add extra semantics beyond what the schema already provides; it merely lists the searchable fields (company, brand name, product NDC, application number) that correspond to parameters. 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 clearly states the tool's function: 'Search the National Drug Code (NDC) directory by labeler company, brand name, product NDC, or application number.' It uses a specific verb ('Search') and resource ('NDC directory'), and distinguishes itself from siblings by listing return fields and naming related tools for other data types.

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 provides explicit guidance: it notes that drug products are not linked by FEI and recommends using the tool with company name to find drugs at a company. It also names related tools (fda_search_drugs, fda_drug_labels, fda_search_nsde) with their purposes, effectively telling the agent when to choose an alternative.

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