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

The annotations already establish that this is a read-only, open-world lookup. The description adds useful behavioral context by naming OpenStreetMap Nominatim and describing the return shape as a "State, Country code" region plus full address. It does not mention rate limits, no-result behavior, or provider attribution requirements, which keeps it from a 5.

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?

The description is front-loaded with the core action and covers the two modes and return value in two tight sentences. There is no redundant or filler language.

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 simple geocoding tool with no output schema, the description gives enough context about modes, provider, and return values for an agent to call it correctly in most cases. The main remaining gap is that the mutually exclusive input combinations and no-result behavior are not stated.

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 only 33%, with only the query parameter documented in the schema. The description compensates partially by mapping place name/address to forward lookup and coordinate to reverse lookup, but it does not explicitly name lat/lng, clarify that both are needed for reverse geocoding, or state that query and coordinates are alternative inputs.

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 specific verb, "look up," and names both supported modes: forward place/address lookup and reverse coordinate lookup. It also names the underlying provider and the returned region/address, so an agent can distinguish it from sibling tools such as get_route or parse_map_link.

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 clearly signals when each mode applies: use a place name or address for forward geocoding, or a coordinate for reverse geocoding. It does not explicitly compare against sibling tools or state exclusions, but the usage context is clear enough for selection.

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