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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful behavioral context beyond annotations by clarifying that exactly one record is returned and that category filtering defaults to all categories. No contradiction with 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?

A single, efficient sentence with no filler. The core lookup behavior and default category behavior are front-loaded, making it easy for an agent to parse quickly.

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 simple read-only exact lookup with two well-documented parameters, an output schema, and strong annotations, the description is nearly complete. It could be slightly stronger by pointing to sibling search tools for non-exact queries, but that is a minor gap.

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%, with reg_no including an example and category fully documenting defaults and allowed values. The description reinforces the 'all categories by default' behavior but does not add much beyond the schema.

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 states a specific verb ('Return') and resource ('one exact NPRA record'), and 'searching all categories by default' adds useful scope. It does not explicitly name sibling tools, but the word 'exact' distinguishes this lookup from search/find tools.

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 implies this tool is for exact registration-number lookups, especially when category is unknown. However, it does not explicitly tell the agent when to prefer search_pharma or find_by_manufacturer, nor does it state exclusions such as 'do not use for partial or fuzzy matches.'

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