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

Annotations already declare read-only, idempotent, closed-world, non-destructive behavior, so the safety profile is covered. The description adds genuinely non-obvious operational context: figures come from FSC quotes reflected the next business day, plus DART disclosures only. It does not describe the response shape or how sections are keyed, which matters because no output schema exists.

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, front-loaded with the Korean name and then a scannable enumeration of contents, ending with the data-source caveat. It is long but every clause adds a distinct content category or constraint. Slightly heavier than ideal for a zero-parameter tool, but no filler.

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 zero-parameter, no-output-schema tool, the description covers what is returned, the time window (previous trading day, next-business-day reflection), and the data provenance. The main remaining gap is the structure of the returned payload, which the agent must discover by calling.

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 and the baseline applies. The enumerated content items effectively define what the implicit snapshot covers, which is the useful analogue of parameter semantics here.

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 names a concrete resource (daily market snapshot) and enumerates exactly the contents: KOSPI/KOSDAQ/KOSPI200 moves, advancers/decliners, sector strength, top movers, 52-week extremes, disclosures, dividend record dates. That is far more specific than a title restatement and lets an agent distinguish a market-wide overview from siblings like sectors, rank, or breakdown. It stops short of explicitly naming those siblings as alternatives.

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 tool is a one-call market summary anchored to the previous trading day. There is no explicit when-to-use vs. when-not guidance, and no routing to alternatives such as sectors for sector detail or disclosures for filing-level detail. The data-source constraint is the closest thing to a scoping rule.

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