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

Annotations already provide readOnlyHint, openWorldHint, and idempotentHint, so the description only adds value beyond those. It adds context about the data source (NCCIH), the scope (~56 herbs), and the output structure (science, side effects, references). It does not, however, describe behavior on an unknown herb (e.g., error vs. empty result), which would have pushed it to 5.

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 slightly longer than necessary but each sentence earns its place: purpose, scope, and routing to a sibling. The main purpose is front-loaded in the first sentence, and the sibling guidance is at the end. No fluff or redundancy.

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 one-parameter, read-only lookup with no output schema, the description is complete. It states the tool's source, what content the output contains, the set of valid inputs, and when to choose a sibling instead. An agent has enough to invoke it correctly without further clarification.

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%, so the baseline is 3. The description adds extra meaning by listing example herbs (turmeric, ginkgo, echinacea, garlic, ginseng, milk thistle, St. John's Wort) and explicitly scoping the parameter to the ~56 covered herbs, while also hinting that vitamins/minerals are out of scope. This goes beyond the schema's bare 'fuzzy-matched' note.

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 opens with a specific verb-resource pair: 'a popular herb's science-and-safety summary from NIH's NCCIH 'Herbs at a Glance' series' and enumerates the contents ('what the science says, side effects and cautions, and key references'). It also names a sibling alternative (supplement_factsheet) for out-of-scope items, which differentiates it clearly without opening the schema.

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 explicitly states when to use this tool versus an alternative: 'For a vitamin, mineral, or the handful of botanicals ODS does cover (ashwagandha, black cohosh, valerian), use supplement_factsheet instead.' It also clarifies that the tool covers the ~56 herbs for which ODS has no fact sheet, giving an unambiguous selection criterion.

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