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

With no annotations, the description carries the full burden. It hints at the payload ('local housing facts when available') but never states that this is a read-only lookup, what happens if both zip and city are supplied, whether the check can fail for malformed input, or what an out-of-area result looks like.

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?

A single well-formed sentence with the resource and the returned value both front-loaded. Nothing is padded, though the terseness comes at the cost of leaving core semantics unstated.

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?

A zero-required-parameter lookup with no output schema and no annotations needs more than one sentence; the description omits which of zip/city is mandatory or sufficient, and only vaguely gestures at return content. An agent cannot reliably construct a valid call from this alone.

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% and both parameters are undocumented in the schema. The description names 'ZIP code or city', which maps loosely to the two fields, but supplies no format, precedence, or mutual-exclusivity semantics. Note the 'or' hints at alternatives while the schema permits both simultaneously without resolution.

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 check against a named resource (service area) keyed by ZIP code or city, which an agent can distinguish from the quote/pricing siblings. The verb is implicit ('whether ... is in') but the outcome is unambiguous.

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?

No when-to-use guidance, no prerequisites, and no mention of the sibling tools it naturally precedes (estimate_job, get_pricing). An agent must infer that this is a qualification/gate step rather than an action tool.

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