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

With annotations covering safety (non-read-only, non-idempotent, open-world, non-destructive), the description adds real value beyond them: the call is free to the homeowner, a vetted pro calls back within the hour during business hours, and a reference is returned. It does not warn that repeated calls may create duplicate requests, which matters given idempotentHint=false.

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?

Purpose is front-loaded and the routing hint comes last, which is good structure. However, the parenthetical 'a vetted local pro calls back within the hour during business hours' nearly repeats the preceding clause, wasting space in a description that should make every clause count.

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 booking-style tool with no output schema, the description covers outcome ('returns a reference and what happens next'), cost, callback timing, service area, and the sibling check to perform first. Enough for an agent to invoke correctly, though duplicate-request behavior remains unaddressed.

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 schema; the description adds only the consent framing and implies the ZIP matters. Baseline 3 is appropriate since the schema does the heavy lifting with no extra syntax or format guidance added.

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 (Book) and resource (mobile mechanic), plus scope (Las Vegas area) and a precondition (real person who asked, with consent). It also names the sibling tool check_service_area for ZIP verification, so an agent can distinguish it from siblings without opening the schema.

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 a clear precondition (only for a real person who asked, with their consent) and routes the agent to check_service_area first when the ZIP is uncertain. The 'when not to use' case is only implied by the consent constraint rather than stated as an exclusion.

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