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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuinely useful context beyond them: names may appear in non-English languages and some places have no English name, which sets expectations about result quality. It still omits whether the data is live or cached and how results are ordered.

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 tight sentences, front-loaded with purpose and then the data caveat. The appended Korean gloss duplicates the English meaning and is dead weight for most agents, but it is brief and does no harm.

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 six-parameter read-only lookup with no output schema, the description covers purpose, coordinate/radius scoping, the 20 km cap and the language caveat, which is most of what an agent needs. The one real gap is the shape of the returned list (fields per place, ordering, pagination), which neither the description nor an output schema supplies.

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 lat/lng, lang, type, limit and radius_km are all documented in the schema itself. The description's 'radius (max 20 km)' merely restates the schema's 0.5-20 bound rather than adding syntax, defaults, or interaction rules (e.g. whether limit applies per type).

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 (List), resource (landmarks or transport stops/stations), and scope (within a radius of a coordinate), which cleanly separates it from the similarly-shaped gil_hotels_nearby and the rest of the gil_* family. An agent can select it without opening the 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?

The description gives constraints (max 20 km) but never says when to choose this over gil_hotels_nearby or gil_search_city, nor any prerequisite such as needing a resolved coordinate first. Usage is only inferable from the resource name.

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