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

Annotations already declare readOnlyHint=true, so the description doesn't need to restate that. It adds value by explaining the relationship to other tools (the returned geography_level values are valid inputs elsewhere) and the caveat about ACS1 omissions, which helps the agent set expectations. No contradictions with 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?

Two sentences with no fluff. The first sentence states purpose and output; the second gives usage guidance and cross-tool relevance. Front-loaded and efficient, every sentence earns its place.

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 tool is simple (2 params, 1 required), has an output schema, and the description covers purpose and usage. The note about ACS1 omissions and the cross-reference to other tools makes it complete for an agent to call correctly without needing additional information.

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 the schema already documents both parameters thoroughly. The description repeats the dataset schema text exactly and adds no new parameter semantics beyond the schema. Baseline 3 applies because the schema carries the weight.

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 a specific verb ('List') and resource ('geography levels'), and clearly distinguishes itself from siblings by noting it is used to confirm existence before querying and that its output feeds into census_query_data and census_compare_geographies. This makes it easy for an agent to understand what the tool does and how it differs from other census tools.

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 before querying to confirm that the target geography level exists' and notes that ACS1 omits many sub-state levels, providing clear context for when to invoke it. However, it does not explicitly state when not to use it or name an alternative tool for other scenarios, which keeps it just below a perfect score.

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