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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds real value beyond annotations: cross-state scope, the tier-then-name ranking order, and notably the error handling for invalid service slugs ('surface the 9 canonical alternatives'). No contradiction with 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?

Three sentences, all front-loaded: purpose, usage context, then error behavior. No filler or repetition of schema content. Each sentence earns its place, though the last sentence on invalid slugs could arguably be folded into a parameter note.

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?

Comprehensive for this tool: output schema covers return format, annotations cover the safe read/idempotent profile, and the description covers purpose, scope, ranking, and error behavior. Missing only explicit mention of pagination semantics, but the limit parameter and output schema already address results handling.

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 fully documents all three parameters, including the enum values and a pointer to valet_list_services. The description adds minimal value beyond the schema—it echoes the two slugs and hints at the error behavior tied to service_slug, but does not materially extend parameter understanding. Baseline 3 is appropriate given the schema carries the load.

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+resource ('Search valet operators') with precise scoping ('by service slug plus city slug across all matching states'). The cross-state qualifier and 'tier-then-name ranked list' directly differentiate it from city-scoped tools like valet_find_operators_in_city, so an agent can distinguish it without opening schemas.

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 states the trigger condition: 'Use this when an agent has both a service slug and a city slug and wants a cross-state tier-then-name ranked list.' It clearly conveys the context for selection but doesn't explicitly name sibling alternatives or state when NOT to use it, leaving some inference to the agent.

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