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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior, so the description is not burdened with safety disclosure. It does add real value beyond them: the result is filtered to cities with upcoming events, ordered largest-first, and annotated with a count. Minor ambiguity remains around what 'biggest' means (population vs. event volume).

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 dense sentence with zero filler, front-loading the resource and scope before the ordering and return detail. Every clause carries information the agent needs.

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 parameters and no output schema, the description must convey what comes back and in what order, and it does exactly that (cities, filtered to those with upcoming events, largest first, with a count). Nothing needed to invoke a zero-argument list tool correctly is missing.

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?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline is met. The implicit note that results are scoped and ordered is a bonus rather than a substitute for param documentation.

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?

Names a concrete resource (Latvian cities and towns), a scope restriction (only those with upcoming events on EventApp), an ordering rule (biggest first), and the payload shape (with how many). An agent can tell this apart from sibling tools like list_categories or search_events without opening the 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?

Usage is implied rather than stated: the 'upcoming events' qualifier suggests this is an entry-point/discovery call before drilling into search_events or get_event. There is no explicit when-to-use, when-not-to-use, or named alternative, so guidance is only inferred.

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