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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds only the underlying REST endpoint (GET /rxcui), which reinforces read-only but reveals nothing about result ambiguity, multiple matches, or error behavior on unknown names.

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 short sentences with the core purpose front-loaded and no padding. The REST endpoint clause is arguably implementation detail rather than agent-facing value, but it costs only a few words.

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 carries the burden of describing what comes back, and it does not — it never says whether a result is a single RxCUI, a ranked list, or empty when no match is found. Functional but with a clear gap for a lookup tool whose results are often ambiguous.

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 both enums (allsrc, search) are fully documented in the schema, so the description need not repeat them. It adds no parameter meaning beyond the schema, which is the expected baseline 3.

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 and resource ('Find RxNorm concept IDs (RxCUIs)') scoped to a drug name string, which is more precise than the bare title. It does not explicitly distinguish itself from siblings like rxnorm_get_approximate_match or rxnorm_get_spelling_suggestions, so it lands just short of a 5.

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?

No when-to-use guidance, no exclusions, and no routing to alternatives. Given that approximate matching and spelling suggestion siblings exist, an agent gets no signal about when a plain name lookup is the right choice versus those tools.

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