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

Beyond the readOnly/destructive annotations, the description discloses important behavior: there is no transaction price in KR reports, reports are filed within ~5 business days, buy/sell is derived from the sign of share change, a filter with no matches returns count 0 rather than an error, and summary totals cover the entire fetched set regardless of the filter. These are exactly the non-obvious behaviors an agent needs.

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 long but organized into labeled sections (purpose, not-for, args, returns, important, examples, use-when, errors), with the core purpose and sibling differentiation front-loaded. The length is justified by the tool's complexity and every block carries actionable information; only minor repetition of sibling routing exists.

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 moderately complex lookup tool with an output schema and 4 parameters, the description covers input formats, enum semantics, return shape, edge cases (no matches, unknown company), timing, and the no-price caveat. Nothing an agent needs to invoke it correctly is left out.

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, and the description adds meaningful value on top: company can be a 6-digit code, name, or 8-digit DART corp_code; tx_type is tied to positive/negative share change; and response_format choices are mapped to markdown table vs machine-readable JSON. It mostly reinforces the schema but with richer operational meaning.

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 opens with a specific verb and resource: 'Korean insider transactions for a listed KR company' from DART's elestock report, explicitly framed as the Korean equivalent of SEC Form 4. It also distinguishes itself from sibling tools by naming get_edgar_insider_trades and get_edgar_13f as covering US insiders and institutional managers, so an agent can select it correctly.

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?

It provides explicit routing: 'Not this tool for: US insiders... or institutional managers', then repeats the alternatives in the 'Use when' section ('For US insiders use get_edgar_insider_trades. For institutional holdings use get_edgar_13f'). It also gives an error-handling path (unknown company -> search_dart_company), leaving no ambiguity about when to call this tool.

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