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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real context beyond that: the data source ('Pulls from the XP marketplace catalog') and an operational instruction to cache results per conversation rather than re-calling for the same event_id. It doesn't cover failure behavior for an unknown event_id, which is the only notable 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, front-loaded with the usage trigger, then the data source, then the caching rule, then the exclusion. Every sentence contributes a distinct piece of information with no repetition of the schema or annotations.

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 an output schema present, the description needn't document return values, and it correctly focuses on selection guidance, source, and caching. For a simple one-parameter read tool this is nearly complete; only error/edge behavior (e.g. invalid event_id) is 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?

There is a single required parameter with 100% schema description coverage, including where the ID comes from ('search_events or a previous user selection') and a format example. The description adds no further parameter semantics, so the schema does the heavy lifting and the baseline of 3 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?

The description names a specific verb and resource ('full event card' for an event ID) and enumerates what the card contains: venue, performers, fee-inclusive price preview, images. It also explicitly rules out the sibling use case, so an agent can distinguish it from get_ticket_listings and get_venue_details without opening any 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?

It states the triggering precondition ('event ID is in hand'), the intent ('wants the full event card before browsing tickets'), an explicit exclusion ('Do not use to list ticket inventory'), and names the correct alternative ('`get_ticket_listings` is the right tool for seat-level data'). Nothing is left to inference.

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