find_variables

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

With no annotations present, the description carries the behavioral burden and does so reasonably well: it discloses that the metadata index is English-only, that Chinese keywords return nothing, that stemming is applied, and that iterative re-querying is expected. It does not discuss result ranking, pagination, or cost/latency, which are minor gaps for a search tool.

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 content is front-loaded with a bracketed role marker and a ★ callout for the critical keyword rule, and each sentence adds something (language constraint, example, stemming, retry policy). It is somewhat long, and the worked example could be tightened, but it does not feel padded.

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 the description needn't explain return values, and it covers purpose, keyword construction, and retry behavior adequately for a search tool. The main omission is disambiguation from the similarly named search_metadata sibling, which leaves the agent to guess which search surface to use.

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 already 100%, so the baseline is 3, but the description materially adds to the keywords parameter: the concept-expansion strategy, the 3-10 synonym count intent, and a worked example mapping a natural-language question to concrete terms. This goes beyond restating the schema by explaining what a good keyword set looks like.

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 bracketed label identifying this as the primary tool for finding variables and specifies semantic search over variable metadata (definitions, questionnaire text, labels, value labels) across the whole database. The verb+resource+scope are all clear. However, it never names the very similar sibling search_metadata, so the boundary between the two tools is left for the agent to infer.

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?

It gives strong, actionable guidance on how to invoke the tool — expand concepts into multiple English synonyms, prefer over-supplying, rely on stemming, and re-query with new synonyms rather than reporting no results. What it lacks is explicit routing: it does not state when to prefer this over search_metadata, run_query, or variable_stats, so no alternative-selection criteria are given.

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