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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description adds genuinely useful non-annotation context: the metered pricing model (free daily allowance, then $0.001 USDC per call via x402) and the plural 'concept id(s)' hinting multiple matches may return.

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?

Two tight sentences with the matching semantics front-loaded and the cost model second. No filler 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?

An output schema exists so return values need not be explained, and the one-parameter surface is simple. The description covers match type, result shape hint, and pricing, though it does not spell out what 'normalised' means in practice (case, punctuation, salt forms).

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 coverage is 100% with a single optional-free 'name' parameter already described as 'Drug name (ingredient or brand)'. The description adds no syntax, format, or matching-rule detail beyond what the schema provides, so the baseline 3 applies.

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 specific verb (exact normalised match) and resource (drug name to RxNorm concept id(s)). The word 'Exact' implicitly distinguishes it from rxnorm__approximate and rxnorm__spelling, but no sibling is named outright.

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?

Usage is only implied: 'Exact (normalised) match' signals this is the precise-lookup path, leaving the agent to infer that approximate or spelling variants live in sibling tools. No explicit when-to-use or when-not-to-use statement.

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