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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so safety is covered. The description adds value by specifying that the response contains the *full* record across all those fields, which is behavioral context not in the annotations. It omits error behavior for a nonexistent event and whether siteSlug scopes or merely routes the lookup.

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?

A single front-loaded sentence with no filler; the return-field enumeration is dense but every item is meaningful since no output schema exists. The trailing field list reads slightly like a raw dump, which keeps it from a 5.

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 a two-parameter, fully described schema, complete annotations, and no output schema, the description covers the essentials: it establishes the single-record scope and enumerates the returned data. Error handling and the siteSlug/eventId relationship are the only real gaps.

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%; both eventId and siteSlug are documented in-schema, including their patterns and provenance (list_events, list_sites). The description says nothing about either parameter, so baseline 3 applies — no meaning is added beyond the schema.

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?

"Returns one event" names a specific resource and cardinality, and the enumerated fields (description, dates, location, admission, ticketUrl, contactInfo, source, commercial) make it clear this is a full-record fetch rather than a list. The list_events sibling is implicitly distinguished by cardinality, but the description never names it, so it falls short of explicit sibling differentiation.

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?

Usage is only implied: an agent must infer that this is the tool to call when it already has an eventId obtained from list_events. There is no explicit when-to-use, no statement that list_events should be used first to discover IDs, and no guidance for what happens with a stale or unknown ID.

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