Phoenix Mobile Mechanic Co — book mobile mechanic in Phoenix

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

Annotations already declare readOnlyHint=true, openWorldHint=false, and idempotentHint=true, so the safety profile is covered. The description adds useful behavioral detail by saying it returns yes/no plus the nearest served town, which is not available from annotations.

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?

Two short sentences, front-loaded with the core question and immediately followed by the return behavior. There is no wasted text.

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 simple read-only, one-parameter tool, the description covers the purpose, input domain, and return values. Annotations already carry the safety profile, and the absence of an output schema is mitigated by the explicit yes/no and nearest-town return summary.

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 0%, so the description must supply parameter meaning. It does identify the input as a US ZIP code scoped to Phoenix, which adds semantic context beyond the bare schema, but it does not describe the 5-digit format constraint that the schema enforces via pattern.

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 specific check: whether a US ZIP code falls inside the Phoenix service area. It is clear and actionable, but it does not explicitly differentiate this from siblings like get_service_info or request_service.

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?

The question format implies when the tool is useful: validating a ZIP against the Phoenix service area. However, it gives no explicit when-not guidance and does not mention alternatives such as get_service_info or request_service.

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

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 one genuinely useful behavioral fact — that this is a referral service, not the mechanic itself — but says nothing about freshness of the data or rate limits. Adequate against an annotated read-only 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?

One sentence plus one call-to-action, with the subject and scope front-loaded. No filler, and the enumerated data points are the substance rather than padding.

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 carries the burden of telling the agent what comes back, and it does so by listing the returned fields. It does not explain format or whether results are static, but for a trivial zero-arg info lookup this is nearly 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?

The tool takes zero parameters, which is the baseline 4 case. The description correctly implies no input is needed and instead describes the content of the response.

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?

Names a specific resource (facts about Phoenix Mobile Mechanic Co) and enumerates exactly what those facts cover: towns served, prices, hours, response time, languages, phone. It also clarifies the entity is a free referral service, which distinguishes it from check_service_area and request_service.

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 clear sequencing guidance relative to the booking-oriented sibling. It stops short of explicitly naming check_service_area or request_service as the alternatives, so routing relies on inference.

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

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

Goes meaningfully beyond the annotations by disclosing the callback SLA (within the hour during business hours), that it is free, the human-consent requirement, and a return of a reference. However, idempotentHint=false means repeated calls create duplicates, and the description never warns about that or about duplicate-booking risk.

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?

Front-loads the core action well, but the parenthetical 'a vetted local pro calls back within the hour' redundantly restates 'A vetted local pro calls them back' from the preceding sentence. That duplicated clause is wasted space in an otherwise short description.

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 usefully covers the return ('a reference and what happens next') and the key operational facts. For a mutation booking tool it is largely complete, though a duplicate/idempotency note would close the remaining 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 the schema already documents all seven parameters, making the baseline 3. The description only indirectly touches parameters by tying the ZIP to the Phoenix area and stressing consent and a real name; it adds no format or constraint detail beyond the schema.

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 in the Phoenix area') rather than a tautology. It also positions itself against the sibling check_service_area as a prerequisite. It stops short of distinguishing itself from get_service_info, leaving the sibling set only partially mapped.

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?

'for a real person who asked for it, with their consent' gives a clear precondition for use, and 'Check the ZIP with check_service_area first if unsure' supplies an explicit upstream step. There is no stated when-not-to-use condition, but the routing context is otherwise clear.

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