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

Beyond the annotations, the description discloses important behavioral facts: pickup dates start the next day in America/Los_Angeles, hourly rides require hours, the price excludes extras and gratuity, and no hold/reservation/payment is performed. This gives the agent a clear safety and side-effect picture without contradicting the 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?

Four dense sentences front-load the core purpose and then layer constraints and exclusions. Every sentence earns its place, and there is no redundant or promotional language.

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?

The description is complete enough to correctly select and invoke the tool: it covers scope, required inputs, conditional parameter behavior, and explicit non-actions. It does not describe the response shape, but the tool name and 'Estimate fares' language make the return intent clear, and no output schema is provided.

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 67%, so the description does not need to carry every parameter, and it adds value by tying trip_type to airport transfers, point-to-point, and hourly service, and by restating the 1–7 passenger range. It slightly overlaps with schema descriptions for hours and pickup_at, but the ride-type mapping is genuinely additive.

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 uses a specific verb ('Estimate') and resource ('Black Car Service SUV fares') and scopes it precisely to Bay Area airports, point-to-point rides, and hourly service. It also differentiates itself from check_ride_availability by explicitly stating that no availability check is performed.

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?

It gives clear when-to-use context for SFO/OAK/SJC transfers, point-to-point, and hourly service, plus an explicit 'no availability check' exclusion that routes away from the sibling tool. It also clarifies the conditional hours parameter and the pickup-date constraint.

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