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

With no annotations, the description carries the full burden. It discloses the payment mechanism, the 402 retry with a PAYMENT-SIGNATURE header, and the ranking order, which are non-obvious behaviors. It does not describe result format or error cases, but for a read-only scanner this is adequate.

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 moderately long but every sentence adds value: payment, retry, cold-start workflow, and sibling comparison. It is front-loaded with the primary purpose, with only slight redundancy in multiple commas and promotion ('BEST COLD START', 'no commitment') that could be trimmed.

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 single-parameter tool without output schema, the description includes all necessary invocation context: universe, ranking, payment mechanism, retry header, and the alternative tool. An agent knows exactly how to call it correctly and what to expect in return.

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% for the single `limit` parameter, so the description is not required to elaborate. It adds no extra parameter-specific meaning beyond the default (5) and max (50), so a baseline 3 is appropriate.

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 first sentence states a specific verb+fefine resource ('Korean market snapshot (KOSPI+KOSDAQ)') and outcome (return stocks at a bottom ranked). It distinguishes itself from sibling `scan_tops` (opposite direction) and `pitch` (count vs names).

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 explicitly says 'BEST COLD START' and routes users to `pitch` for a count when only a count is needed, and to this tool for names. It clearly tells the agent this tool requires payment, while `pitch` is free, giving a usable decision rule.

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