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

Annotations already cover readOnlyHint and openWorldHint, yet the description adds substantial behavior the agent could not otherwise know: caching of fresh lookups, a shared one-call-per-second rate limit across all workers, the fact that no points are spent, and the privacy_consent_required failure mode. The only drag is the puzzling "if you supply fields" clause, which does not map cleanly onto the one-parameter schema and muddies an otherwise strong disclosure.

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 purpose is correctly front-loaded in sentence one and the licensing/rate-limit details are legitimate. However, the closing sentence about supplying fields and controller privacy acceptance is tangential and confusing for a tool whose schema accepts exactly one field, spending words on a scenario the agent may never encounter.

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, single-parameter lookup with no output schema, the description covers cost, rate limits, caching, auth/privacy failure mode, and licensing — an unusually complete behavioral picture. The remaining gap is that with no output schema present, the description never indicates what the coordinate response looks like (format, single vs. multiple matches).

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 0% for the single required parameter q, so the description must carry the load. It does add real meaning (q is a place name, not a URL, singular), but it never mentions the 1-60 character constraint or the expected input shape beyond "place name," so compensation is partial.

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 opens with a concrete verb and resource: "Turn one place name into coordinates" via the public Nominatim service, which tells an agent exactly what comes out. It does not name any sibling (hub_postal, hub_wikidata, hub_transit) or explain why to pick this one for location lookup, so the differentiation gap keeps it from a 5.

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?

"Turn one place name" and "does not accept a URL" imply the usage boundary (single free-text place, no batch, no URL input), which is useful implied guidance. But there is no explicit when-to-use/when-not-to-use statement or named alternative among the hub_* geodata siblings, leaving the agent to infer selection.

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