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

Annotations already cover readOnly/idempotent/openWorld/non-destructive, yet the description still adds meaningful behavior: results are ordered best-match-first, ranked purely by text similarity with no clinical validation, only RxNorm-source names are returned, and each call costs 1 credit. These are non-obvious caveats an agent could not infer from structured fields.

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?

Front-loaded with the core question and the matching behavior, then caveats, then cost. Dense and largely waste-free; the parenthetical credit note and repeated 'name-plus-strength' phrasing are minor 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?

With no output schema, the description does the work of explaining returns: closest RxNorm concepts, RxCUI codes, best match first. For a simple two-parameter read tool this is nearly complete, though the exact response fields and how many candidates appear by default are left implicit.

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% and the schema already carries the term format example ("zocor 10 mg") that the description echoes. The description says nothing about the limit parameter (range, default) beyond what the schema documents, so it adds little parameter meaning.

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?

States a concrete verb and resource (match a messy drug name/brand/strength to RxNorm concepts and RxCUI codes) and scopes the source (NLM RxNav approximate match). It is clearly separable from sibling tools like drug_spelling_suggest, drug_brand_names, or drug_generic_ingredient, which return different artifacts.

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?

"Useful as the first step for medication lists, reconciliation and any tool that needs an RxCUI" gives a clear usage context and ordering relative to downstream tools. It also states exclusions (non-US brand names may not match, text-similarity ranking rather than clinical checking) but never names a specific sibling alternative, so it stops just short of a 5.

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