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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the closing 'Read-only' only echoes structured data. The valuable addition is the field list (description, address, dates, capacity, tickets sold, sales amount, category, host), which sets expectations for the response in the absence of an output schema. It does not mention what happens for a missing id, which keeps it from a 5.

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?

Two sentences and a fragment, with the operation and the returned fields front-loaded. The sibling pointer is appended where it belongs, and nothing is repetitive or filler.

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 returned-field enumeration is the key thing an agent needs and it is present. Error behavior for an invalid or missing id and the distinction from universe_list_events are the remaining omissions, minor for a simple getter.

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?

There is a single required parameter, and the schema documents it (eventId, 100% coverage). The description adds only the 'by id' framing, no format, source, or retrieval guidance beyond the schema. Baseline 3 for a fully documented single parameter.

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 ('Fetch one event by id') and then enumerates the returned fields. It also names the sibling that handles a different resource (universe_list_ticket_types), so an agent can separate the two 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?

The description tells the agent that ticket types are not part of this call and routes it to universe_list_ticket_types, which is a real alternative. It stops short of saying what to do when the id is unknown or when to prefer universe_list_events, so it is a clear usage context rather than a full when/when-not rule.

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