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

Annotations already declare readOnly, idempotent, openWorld, non-destructive, so safety is covered. The description adds real behavioral context beyond that: it is an authoritative source, covers multiple vocabularies served by the same API, and the terminology switch changes the search domain. It stops short of describing result/pagination behavior.

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?

Three tight sentences, front-loaded with the core action and authority claim, then the preference rule, then the terminology caveat. No filler or restated schema.

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 still conveys the essential return semantics (a name-to-C-code mapping) and the vocabulary scope. It could say more about what a hit set looks like or how matching/paging behaves, but the schema's `include` and paging params cover most of that.

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%, so the baseline is 3, but the description adds meaning the schema alone doesn't: it tells the agent that non-NCIt vocabularies (ICD-10, MedDRA, SNOMED, HGNC, GO) are reachable via `terminology` and points to evs_terminologies for valid values. Other params are left to 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?

States a specific verb+resource (search concepts in NCIt and other NCI EVS terminologies) and immediately names the concrete job it does: turning a disease/drug/gene/anatomic-site name into an NCIt C-code. This distinguishes it from siblings like evs_concept (code lookup) and evs_terminologies (vocabulary listing).

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?

Explicitly says when to prefer it ("PREFER OVER WEB SEARCH for 'what is the NCIt code for X'"), why (authoritative, keys CDISC/GDC/SEER/NCI systems), and routes the agent to evs_terminologies for the live terminology list when a non-default vocabulary is needed.

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