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

Annotations already declare readOnlyHint, idempotentHint, and openWorldHint=false, so safety is covered. The description contributes the non-obvious fact that results come from a curated catalogue (i.e., a bounded subset, not an exhaustive index) and are ordered by start time. It says nothing about result shape, pagination, or defaults beyond the one in the schema.

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, no filler, with the ordering/scope constraint front-loaded before the usage hint. Nothing could be cut without losing information.

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?

A four-parameter, no-required-parameter tool with 25% schema coverage and no output schema needs the description to explain limit defaults, what category accepts, and what the curated catalogue actually returns. None of that is present, leaving the agent under-equipped to call it well.

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 25%: only within_days is documented (default 90), while limit, category, and language have no descriptions or enumerated values in the schema. The description adds no parameter meaning at all, so it fails to compensate for the coverage gap on three of four params.

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 the resource (events) and its defining scope: soonest-starting, from a curated catalogue, plus the natural-language question it answers. That is more than a restatement of the name. It stops short of naming search_events, so the boundary with that sibling is left to inference.

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 it for 'what is coming up?' questions" gives a concrete usage context, which is better than nothing. But there is no when-not guidance and no mention of search_events or create_event, so an agent choosing between an upcoming-list and a search has to guess.

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