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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description's real contribution is the date-overlap semantics ('running at any point between'), which is behavior the schema's bare 'YYYY-MM-DD' does not convey. It says nothing about result ordering, the default limit of 12, or how results are truncated at 40.

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 clause with no wasted words, and the scoping rule precedes the optional filter. It reads as a noun phrase rather than a sentence, and a little more could have been said about return shape at near-zero cost.

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?

The tool is simple, every parameter is documented in-schema, and annotations carry the safety profile, so an agent can call this correctly from the current text. The only gap is return-shape guidance, which is absent because there is no output schema; for a read-only list tool that is a minor omission.

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?

At 100% schema coverage the schema already defines all four parameters, including area examples, date format, and limit bounds with default. The description confirms area is optional and clarifies date matching as overlap rather than containment, which is genuine added value — but the baseline for full coverage is 3.

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 the specific resource (Korean festivals and events) and states the selection rule — anything running at any point between two dates, optionally narrowed to one region. That overlap semantics is meaningfully more precise than a generic 'list' verb. It does not need to differentiate from siblings since none of them return festivals, though it could have explicitly said so.

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?

'Optionally in one region' implies the filter is discretionary but there is no statement of when to reach for this tool versus search_places or find_nearby_places, and no exclusions or prerequisites. Usage is inferable from the resource name alone rather than articulated.

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