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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds meaningful context beyond them: the transaction happens externally on the booking page, nothing is held or charged, and the URL must be relayed verbatim. It doesn't mention link expiry or stability, but the core behavioral picture is solid.

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 short sentences, front-loaded with what is returned, followed by the transaction boundary and the output-handling rule. No filler or repetition.

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?

Four parameters, no output schema, full schema coverage, and rich annotations. The description fills the remaining gap by describing what the return contains and how to use it, and by making clear the tool is a pointer to an external checkout rather than a booking commit.

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% and the parameter docs are already strong, including the HH:MM format warning and the tour_id cross-reference. The description adds nothing parameter-specific, so the baseline 3 for high-coverage schemas applies.

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?

Specific verb and resource: 'Returns the official American Ghost Walks booking link for a tour, plus what to pick on its calendar.' It's clearly a link-generation tool, distinct in kind from get_availability or search_tours, though no sibling is named explicitly.

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?

Draws the boundary clearly: 'The guest chooses the date, time and tickets and pays on that page; this tool does not reserve or charge anything,' which tells the agent this is not a booking action. It also instructs how to handle the output ('Share the returned URL exactly as given'). No explicit alternative-tool routing is given.

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