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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world behavior, so the bar is low. The description adds real value beyond that: it characterizes the answer as deterministic and discloses the response shape (reason, served zips, excluded zips, alternative businesses on a no).

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 front-loaded sentence with the verdict semantics first and the return payload second. No filler, no redundancy with the title.

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?

With no output schema, the description usefully covers what comes back and does so in one clause. However, for a 3-parameter tool it leaves the emergency parameter's semantics entirely unaddressed, which is a meaningful gap for correctness.

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 only 33%: zip is documented in the schema, but slug and especially emergency are not. The description implicitly ties 'this business' to slug and 'customer's zip' to zip, but it says nothing about what the emergency flag does, so the largest documentation gap goes unfilled.

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 and resource: a deterministic yes/no on whether a business serves the customer's zip. This is uniquely distinguishable from siblings like get_business or search_businesses, which return entity or list data rather than a coverage verdict.

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 yes/no framing, but there is no explicit statement of when to call this versus search_businesses, get_service_requirements, or get_availability, and no stated prerequisites. It is adequate but leaves routing to inference.

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