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

Annotations already declare readOnlyHint=true, idempotentHint=true and openWorldHint=false, so the safety profile is covered. The description adds genuinely useful framing — that this is a free referral service rather than the mechanic itself — but says nothing about response size, freshness, or rate limits beyond that.

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?

One colon-delimited sentence plus a short imperative; the resource identity is front-loaded and the field list follows immediately. Slightly dense but no wasted sentences.

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 and no parameters, the description does the needed work by listing the returned facts and stating the pre-booking timing. Only the absence of any freshness or scope caveat keeps it below complete.

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?

There are zero parameters, so the baseline is 4. The description usefully redirects that budget toward output semantics by enumerating the fields the caller will receive (prices, hours, response time, languages, phone), which is more than the empty schema conveys.

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 names a specific resource (NOLA Mechanic, a free referral service for mobile mechanics in New Orleans) and enumerates the data it returns: towns served, prices, hours, response time, languages, phone. It is clearly distinguishable from check_service_area and request_service, though it never names 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?

"Call this before recommending or booking" gives an explicit trigger condition that implicitly routes the agent away from the booking sibling. It stops short of naming when-not-to-use or naming check_service_area as a complement, so it is clear context rather than full alternatives coverage.

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