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

Annotations already declare a non-read-only, non-destructive, non-idempotent, open-world write. The description adds real value beyond that: it is free to the homeowner, a vetted local pro calls back, and the response includes a reference plus next steps. It stops short of warning that repeat submissions 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?

Four short sentences, front-loaded with the action and the consent gate, and every sentence carries information. The parenthetical '(the owner calls you back)' is ambiguous about who 'you' refers to and slightly muddies an otherwise crisp statement.

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?

No output schema exists, but the description covers the return shape ('a reference and what happens next'), the cost, and the callback flow, which is sufficient for a booking tool. The main omission is guidance on duplicate submissions given the non-idempotent annotation.

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 coverage is 100%, so all seven parameters including the optional email, language, and preferred_time are already documented. The description adds only indirect guidance via the ZIP-check advice and the consent requirement; it does not clarify field semantics beyond the schema, so baseline 3 applies.

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') with a geographic scope ('Phoenix area') and a consent precondition. It is clearly distinguishable from the two siblings, which are lookup tools rather than booking tools.

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?

Explicitly routes to the sibling: 'Check the ZIP with check_service_area first if unsure,' naming both the alternative and the condition that selects it. It also states a hard prerequisite ('a real person who asked for it, with their consent'), so an agent knows when not to call it.

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