search_variables

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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds behavioral detail: it's substring search, advises short fragments, and explains that empty results may indicate a wording mismatch rather than unavailability. This goes beyond the annotations and helps the agent interpret outcomes correctly.

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 concise sentences, front-loaded with the primary purpose and immediate alternative. The guidance is efficient without excess wording. It could be slightly more structured (e.g., bullet points), but it's still very readable and scannable.

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?

The description covers usage alternatives and query behavior, and the presence of an output schema covers return value documentation. However, it omits the meaning and usage of category_1/category_2, and 'top' pagination is not explained. For a tool with four parameters and no schema descriptions, more detail is needed for full context.

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 0%, so the description must compensate for parameter meaning. It partially explains the 'query' parameter (short fragment, not full question) but says nothing about 'top', 'category_1', or 'category_2'. These are left undocumented, and the description does not bridge that gap for the majority of parameters.

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 states 'Search all Codebook variables' – a clear verb and resource. It also distinguishes itself from search_indicators by directing to that tool for headline measures, so the agent can tell them apart. It doesn't explicitly differentiate from list_variables or other search-like tools, but the purpose is unambiguous.

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?

The description explicitly says 'use search_indicators for headline measures' – providing a clear alternative and when to use it. It also advises using a short fragment and suggests topics_index as a fallback when results are empty. This gives concrete guidance on when to use this tool versus alternatives.

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