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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and closed-world scope, so the safety profile is covered. The description adds the comparison dimension list, which hints at the response content, but says nothing about output format or behavior with stale/invalid ids; adequate but not rich.

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 short sentences, front-loaded with the core action and cardinality, with the prerequisite second. No 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?

For a one-parameter tool with no output schema, the description covers what is compared and where ids come from, which is most of what an agent needs. It stops short of describing the return shape or edge-case behavior with fewer than 2 valid ids.

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 a single parameter at 100% schema description coverage, the schema already documents the ids array and its 2–4 bounds. The description only restates its provenance ("Use ids from search_events"), adding no new syntax or semantics, so this is baseline territory.

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 (compare) with a bounded resource (2–4 events) and enumerates the dimensions compared (dates, place, price, size, audience, sectors, suitability), so an agent can distinguish it immediately from get_event (single fetch) and search_events (discovery).

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?

"Use ids from search_events" establishes the required upstream workflow, which is the key usage fact. It does not state exclusions (e.g., use get_event when you only need one event's details), so it stops short of full when/when-not guidance.

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