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

Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the safety profile is covered. The description adds two pieces of genuinely useful context beyond that: the call is free, and it returns a location_code intended for downstream use. No mention of ambiguity handling when a place name matches multiple locations.

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 short sentences, zero filler. The what-it-does clause comes first and the downstream-usage instruction follows, which is the correct front-loading for a resolver tool.

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 one-parameter lookup with full annotation coverage and no output schema, this is close to complete: it says what it returns (location_code) and where to use it. The only omission is behavior on ambiguous or no-match results, which is a minor gap rather than a blocker.

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 100% and the single `q` parameter already has an example, so the baseline is 3. The description earns above baseline by enumerating the kinds of place names accepted (city, county, state, country), which clarifies the expected input granularity beyond the schema example.

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 ("look up") and resource ("location codes") plus the accepted granularity (city, county, state, country). It also distinguishes itself from the sibling start_search by naming it as the consumer of the output.

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 sentence "Use the returned location_code in start_search" gives a clear workflow context: call this first to resolve a place name into an ID. It stops short of explicit when-not-to-use guidance (e.g. what to do if a search term is already a code), so it is strong but not exhaustive.

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