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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world); the description adds real behavioral context beyond them: the Asia/Seoul timezone, how the weekend window collapses on a Sunday, and that every result carries its festivaltimes.net URL with a citation instruction. Pagination/result-cap behavior is left to 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?

Three tight sentences: scope first, edge case second, usage example and citation duty last. Nothing is redundant with the schema and every clause carries 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?

For a two-parameter read-only list tool with full schema coverage, no output schema, and annotations covering safety, the description supplies everything needed: window definition, timezone, filter scope, and what results contain.

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 coverage is 100% and the region parameter already documents accepted Korean province/city forms, so the schema does the heavy lifting. The description only restates that region is an optional filter, adding no new semantics.

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 and resource ("List festivals in South Korea") plus a precise temporal scope (this coming weekend, Saturday-Sunday, Asia/Seoul) with the Sunday edge case resolved. It doesn't name the overlapping sibling search_festivals to say how this differs from a general festival search, so 4 rather than 5.

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?

Gives a concrete trigger example ("이번 주말 경기도 축제"), which tells the agent the intent this tool serves. There is no explicit when-not or pointer to search_festivals for other date ranges, so the routing guidance is clear but incomplete.

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