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

Annotations already declare readOnly=false, openWorld=true, idempotent=false, and destructive=false. The description adds useful behavior beyond that: the callback happens within the hour during business hours, the service is free to the homeowner, and a reference is returned. Auth and error details are absent, but those are less critical for this action tool.

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?

The action is front-loaded, but the second sentence redundantly repeats the callback promise: 'A vetted local pro calls them back (a vetted local pro calls back within the hour during business hours).' That repetition and the trailing 'Check the ZIP...' add some waste, so it is adequate but not tight.

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 informs the agent that a reference and next steps are returned. Combined with 100% schema coverage and annotations, it covers most of what an agent needs: consent, area, timing, cost, and pre-check sibling. It omits explicit failure or out-of-area handling, but check_service_area partially covers that gap.

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 100%, so all seven parameters are already documented in the input schema. The description adds no parameter-specific syntax or meaning beyond what the schema provides, which fits the baseline score when the schema does the heavy lifting.

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 verb and resource ('Book mobile mechanic'), names the geographic scope ('Boise area'), and adds the consent prerequisite. It also references sibling check_service_area for ZIP validation, so an agent can distinguish this action tool from that check tool.

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?

Gives clear usage context: use for a real person who asked and consented, and consult check_service_area first if the ZIP is uncertain. It does not explicitly contrast with get_service_info or state when not to use this tool, so it stops short of full when/when-not guidance.

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