Request a 99 ride (gated)

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

Annotations already mark this as destructive and non-read-only, and the description adds substantial context: fail-closed behavior, environment variable gating, explicit user intent, guest token charging restrictions, and example defaulting. This is exactly the kind of safety-critical behavioral disclosure that prevents accidental paid or destructive calls. 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?

The description is four short clauses with no filler, and the 'Fail-closed' warning is front-loaded. It is appropriately telegraphic for a gated mutation tool, though the lack of an action statement makes it slightly cryptic.

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?

There is no output schema, yet the description never explains what a successful call returns or how to consume the ride result. It also does not place the tool in relation to siblings like ninenine_estimate, ninenine_active_ride, or ninenine_cancel_ride. Gating is covered well, but operational context for an agent is incomplete.

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 only 14%, and the description does not compensate. It adds nothing about from_lat/from_lng/to_lat/to_lng, category, or response_format. It only reinforces explicit_user_intent, which the schema already documents, leaving several parameters effectively unexplained.

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 never explicitly states that this tool places a ride request; it jumps straight to gating details like 'Fail-closed' and NINENINE_ALLOW_MUTATIONS. The action is recoverable only from the name/title and the indirect 'charge' wording, making the description itself vague about the tool's actual operation.

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 description gives clear conditions: NINENINE_ALLOW_MUTATIONS and explicit_user_intent are required, guest tokens cannot charge, and default examples should not enable it. This tells an agent both when it is permitted and when it should not be invoked. It does not compare against siblings like ninenine_estimate, but the gating guidance is concrete.

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