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

Beyond the readOnly/idempotent annotations, it discloses data freshness (previous trading day's close), warning behavior for liquidation/suspension stocks, and how the response should be cited (quote the reference date verbatim, do not relabel as 'today'). These are non-obvious traits an agent would otherwise guess wrong.

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?

Front-loaded with the core purpose, then escalation warnings and usage constraints; every sentence conveys a distinct fact. Slightly long, and the date-quoting instruction, while useful, sits mid-paragraph rather than being grouped with the other output guidance.

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?

With no output schema, the description carries the burden and does so: it explains what the response contains, what the omitted-signal mode returns, how anomalous stocks are flagged, and how to handle the reference date. Nothing needed to call it correctly is missing.

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%, so the baseline is 3, but the description adds real semantics: omitting signal returns only per-list counts rather than stock rows, which changes how an agent should call it. It does not add anything for limit/cursor/format, hence not a 5.

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?

Specific verb+resource: it queries which stocks appeared on which signal list on a reference date. It also explicitly distinguishes the two modes of the tool (index of counts when signal is omitted vs. per-list contents when supplied), so an agent can tell it apart from siblings like maedong_stock_signals.

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?

States when to use it (first, to pick a list when signal is omitted), the explicit exclusion ('do not use to generate buy/sell decisions'), and the operating context (past statistics, previous day's close). That is when, when-not and rationale all present.

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