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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds value beyond them: the US-only scope (implying out-of-country coordinates fail) and the fact that the full containing-geography set is returned rather than a single match. It stops short of stating rate limits or error 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?

Two sentences, zero waste: the first defines scope and return payload, the second gives selection guidance. The emphasized headers make it front-loaded 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?

With no output schema, the description usefully enumerates the returned geographies, and annotations carry the safety profile. It leaves the vintage and benchmark parameters unexplained (beyond schema defaults), which is a minor gap for a tool whose output shape depends on them.

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 latitude, longitude, vintage and benchmark are all documented in the schema; baseline 3 applies. The description adds no extra semantics for vintage or benchmark (e.g. what changing vintage does to returned GEOIDs), so it does not exceed 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 (reverse geocode) with an explicit input constraint (lat/long inside the United States) and enumerates the exact resources returned (state, county, tract, block, place, congressional/school district, urban area). An agent can tell this apart from a forward-geocoding tool like census_geocode_address without opening either schema.

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 names the trigger condition ('when you have a coordinate and need the tract or block GEOID') and routes away from an alternative ('PREFER OVER WEB SEARCH'). It does not explicitly contrast with the closer siblings census_geocode_address and census_geocode_batch, so the routing guidance is clear but not exhaustive.

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