get_market_calendar

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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds valuable behavioral context: returns info for 3 business days (previous, current, next), all times in KST, and empty sessions on closed days. This goes beyond the safety profile but does not describe the exact response structure, though that is covered by the output 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?

The description is concise, with each sentence serving a distinct purpose: purpose, use case, return characteristics, and argument definitions. No redundant or filler content, and it is front-loaded with the main purpose.

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?

Given the readOnly annotation, simple parameter set, and existence of an output schema, the description covers all necessary context: input values, timezone, business-day scope, and closed-day behavior. It is fully adequate for an agent to invoke the tool correctly.

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 0%, so the description fully compensates by defining both parameters: country accepts 'KR' or 'US', and date is an optional YYYY-MM-DD string. This completely clarifies parameter meaning and formats, addressing the coverage gap.

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?

The description clearly states it retrieves market operating hours for KR or US markets and explicitly mentions it is used to check if the market is open. This distinguishes it from sibling tools like get_price or get_candles, which focus on market data rather than market hours.

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?

The description provides a clear use case ('지금 장이 열려 있는지 확인할 때 쓴다' — use when checking if the market is open). However, it does not explicitly mention alternatives or when not to use this tool, so it lacks the 'when-not/alternatives' component for a perfect score.

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