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

Annotations already declare readOnly, idempotent, open-world, non-destructive, so the safety profile is covered. The description adds useful behavioural detail beyond that: the concrete output example shows what a lookup actually yields, including the timezone string format, which tells the agent what to expect to consume. Auth, rate limits, and ambiguity handling are not mentioned.

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 tight sentences: what it does, when to use it, then a worked example. Purpose and trigger are front-loaded and nothing is wasted.

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?

An output schema exists so return structure need not be documented, yet the description still previews the returned fields and gives an example mapping. For a two-parameter readonly lookup, nothing an agent needs in order to call it correctly 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 description coverage is 100%, so both lat and lon are already documented with ranges and sign conventions. The description only restates the pairing via the example call, adding little meaning beyond the schema; a baseline 3 is appropriate.

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 and resource — resolve coordinates to a human-readable place — and enumerates the returned fields (city, state, county, timezone). It does not name the sibling search_locations, which is the obvious forward-geocoding counterpart, so the differentiation is implicit rather than explicit.

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?

"Use when you have lat/lon but need a display name or the local timezone" gives a clear selecting condition and cleanly implies this is for coordinate input rather than name input. There is no explicit when-not statement or named alternative tool, which keeps it short of a 5.

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