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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so safety is covered, and the description adds non-obvious behavioral facts: the operation is mutating and the new group is created empty. It does not discuss permissions, error cases or what the response contains, but the output schema exists, so this 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 dense sentences, front-loading the action and its payload, then prerequisites, then the sibling alternative. No filler or restatement of the title.

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 20-param mutation with annotations and an output schema, the description supplies the essential workflow (event ID source, empty-group caveat, ticket-type follow-up, escaping to create_event). The remaining shortfall is the thin coverage of individual optional fields.

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?

With 20 parameters at only 10% schema description coverage, the description must carry the semantics, yet it only name-drops broad groupings. Many inputs remain unexplained — status, reference, preselect, feeDisplay, layout internals, and the four hideWhen* booleans — so an agent still cannot tell what setting them does beyond their enum values.

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 ("Add") plus resource ("one ticket group to an existing event"), and it enumerates the sub-concepts the group carries (capacity, sale window, availability trigger, selection type, discounts, display options). It also names the sibling it is not (create_event), so an agent can distinguish it without opening the 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?

Explicit routing is given: get the event ID from list_events, add the group's ticket types afterwards with create_ticket_type, and use create_event instead when creating an event together with its tickets. Conditions for the alternatives are stated, not inferred.

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