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

Annotations already cover readOnly/idempotent/non-destructive, so the bar is lower; the description adds genuinely new behavioral context by stating the tool 'charges nothing and sends no payment prompt' and that the guest completes the purchase. It doesn't mention link expiry, auth requirements, or whether the same event+tier yields a stable link.

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 tight sentences, front-loaded with the return value, followed by the critical behavioral clarification and the sibling pointer. No filler or restatement of the name.

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?

With no output schema, the description carries the burden of explaining the return value and does so ('the link ... with the chosen ticket type and quantity filled in'). Combined with the no-payment clarification it is nearly complete; only link lifetime and permission prerequisites are unaddressed.

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 only 33% (eventId and quantity undocumented, tierId documented). The description partially compensates by describing the link as pre-filled with 'the chosen ticket type and quantity' and by pointing to check_event_availability for tierId, but it adds nothing for eventId or for the 1-20 quantity bounds beyond the schema's own min/max/default.

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 and resource ('Returns the link to WaitApp's ticket checkout page for an event') plus the pre-filled scope (tier type and quantity). It also names the sibling it depends on ('check_event_availability shows what is left and the ticket types'), so an agent can route correctly without opening either schema.

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?

Gives a clear use context (guest opens the link and pays themselves) and explicitly routes to check_event_availability as the source of tierId. It stops short of naming the negative alternative (get_payment_link) or when not to use this tool, so it is strong but not fully explicit on exclusions.

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