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

Annotations only declare readOnlyHint=true, so the description carries most of the behavioral burden and does add real context: 'Works offline' discloses no network dependency, ISO 3166-2 / FIPS disclose the precision and coding system of results, and the map sentence discloses an artifact-producing side effect not visible in annotations. It stops short of describing the return shape, ordering, or failure behavior for out-of-range or ocean coordinates.

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 short sentences, front-loaded with the primary operation before the conditional map mode. No filler, no restatement of the title, and each sentence contributes new information.

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?

For a read-only, no-output-schema tool this covers what an agent needs to call it: input meaning, geographic resolution, offline behavior, and the optional map side effect. Minor gaps remain around the returned data structure and the 'auto' map mode, but nothing essential to correct invocation is missing.

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 coverage is 33%, so the description must compensate and it only partly does: it clarifies that 'map' enum values correspond to regions of the main country, US counties, or countries. It leaves the 'auto' enum value unexplained and says nothing about 'title', nor about the 5000-point cap or the optional per-point 'name'.

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 uses a concrete verb and resource ('for each latitude/longitude, find the country, its state/province/region (ISO 3166-2) and ... the county (FIPS)') and states output granularity precisely. It also flags the conditional map-drawing behavior, which hints at overlap with the generate_*_map siblings, but it never names an alternative to distinguish itself from them.

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?

Usage is implied rather than directed: the agent learns that setting 'map' adds a rendered map, so the tool is for reverse geocoding optionally paired with a map. There is no explicit when-to-use/when-not, and no guidance on choosing this over generate_country_map, generate_county_map, or generate_pin_map despite the clear functional overlap.

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