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 adds genuinely useful context the annotations lack: the entity is a free referral service rather than the plumber itself, which shapes how an agent should present results. It says nothing about data freshness or rate limits.

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 declarative sentence for scope followed by one imperative sentence for usage. The field list is dense but every item earns its place, and the action directive is front-loaded at the end where it is unmissable.

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 zero-parameter, read-only info tool with no output schema, the description enumerates the returned fields well enough that an agent knows what it will receive. Nothing needed to call 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?

The tool takes zero parameters, so the baseline is 4 by rule. The description correctly implies a no-argument lookup by never referencing any input, and the enumerated field list acts as implicit scope documentation rather than parameter documentation.

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 concrete resource (facts about KC Plumb, a free referral service in Kansas City) and enumerates exactly what those facts cover: towns served, prices, hours, response time, languages, phone. It also implicitly separates itself from the booking-oriented siblings by positioning itself as the reference lookup.

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 explicit ordering guidance relative to downstream actions. It stops short of naming check_service_area or request_service as the alternatives, so the routing is implied rather than spelled out.

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