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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so the safety profile is covered. The description usefully adds the return shape ('yes/no and the nearest served town'), which is meaningful since no output schema exists, and its closed-world framing matches openWorldHint=false.

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 with zero filler, front-loaded as the core question with the return contract immediately following. Every clause earns its place.

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 single-parameter read-only lookup, the description covers intent, input domain, and return values, and the annotations cover safety and world assumptions. Nothing an agent needs to invoke 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 0%, so the description must carry the burden; it partially does by specifying 'US ZIP code', which scopes the value to a 5-digit US format consistent with the schema pattern. It does not explain error behavior for malformed or non-US inputs, so it adds only marginal meaning.

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 states a precise verb (check) and resource (US ZIP code against the Corpus Christi service area), phrased as a direct question that an agent can map to an intent. It is clearly distinct from get_service_info and request_service, though it does not name those siblings explicitly.

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?

Usage is implied by the question form — this is a lookup to run when you have a ZIP and need a yes/no answer — but there is no explicit when-to-use, when-not-to-use, or routing guidance toward get_service_info or request_service for follow-up actions.

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