naep_gap_variable_years

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

Annotations already indicate readOnlyHint=true, so safety is covered. The description adds behavioral detail by specifying return fields (innerdiff1, innerdiff2, and the gap between them) and clarifying that it computes group gaps for two years. This adds value beyond annotations.

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 sentences: purpose, example, return description. Every sentence is informative and there is no wasted 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?

Without an output schema, the description compensates by explaining the return values. It also provides an illustrative example. It doesn't cover edge cases like ordering, but given the schema covers parameters, this is adequate for most uses.

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%, so all parameters are documented. The description enriches 'years' by explaining focal and target year semantics, and helps understand the output mapping. This lifts it above the baseline.

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 clearly states the tool compares achievement gaps between demographic groups over time, with a specific verb 'compare' and resource 'achievement gaps'. It distinguishes from siblings like naep_compare_years and naep_compare_groups by focusing on gap change over time, and includes a concrete example.

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 provides a clear context with an example ('Is the racial achievement gap in reading getting bigger or smaller since 2017?') indicating when to use. However, it does not explicitly name alternatives or exclusions, so it stops short of full usage guidance.

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