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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds genuine value with result ordering ('newest first'), the unit (shares), and the presence of the foreign holding ratio. However, the 'recent daily' window is unspecified (how many days?), no pagination or limit behavior is described, and no data-source latency or market-coverage caveats are given, so it does not go beyond a modest addition.

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 no filler, front-loading the resource and investor-type breakdown, then appending the holding ratio and ordering. It is a sentence fragment rather than a full clause, but nothing is redundant.

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?

There is no output schema, so the description carries the burden of describing returns and it does: per-investor-type net buying, units, the foreign holding ratio, and ordering. The remaining gap is the unspecified lookback window for 'recent daily', which matters for an agent judging whether the data answers a given question.

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?

With one parameter at 100% schema description coverage, the schema already defines 'code' as a 6-character Korean stock code with an example. The description adds only the framing 'for one Korean listed stock', which is close to what the schema says, so the baseline of 3 applies.

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 specific resource (daily net buying by investor type) with concrete sub-fields (foreign, institutional, individual), the unit (shares), and an added metric (foreign holding ratio) for one Korean stock. It is clearly distinguishable from kr_quote and kr_price_history, though it does not explicitly carve itself out from those siblings by name.

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: the description says 'for one Korean listed stock', which signals it is a per-ticker lookup taking a stock code. But there is no explicit when-to-use, no stated alternative (e.g., kr_price_history for price, kr_quote for snapshots), and no prerequisites or exclusions.

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