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

The description adds valuable behavior beyond the annotations: the link is meant for the human, not the agent, and the server should never complete the payment flow. This aligns with readOnlyHint and adds human-in-the-loop context. It does not describe the response shape, but that is a minor gap.

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 carry the purpose, usage boundaries, and safety warnings with no filler. The key action and constraints are front-loaded, and every sentence earns its place.

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 single-parameter, read-only retrieval tool, the description covers purpose, usage, and behavioral expectations completely. The schema fully documents the parameter, and the description tells the agent exactly what to do with the result.

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%, and the slug parameter is already well documented in the schema as 'The slug returned by create_reservation.' The description adds no additional parameter meaning, so the baseline score of 3 is appropriate.

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 opens with a specific verb and resource: 'Get a URL for the human to open in their own browser.' It then states the exact purpose, finishing a reservation via phone verification and payment, making it clearly distinct from siblings like get_reservation_status or create_reservation.

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 strong usage context by calling this 'the last step this server ever takes' and explicitly warns against asking for card/OTP data or opening/submitting the URL. It does not explicitly name alternative tools, but the behavioral guardrails make the intended usage clear.

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