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

Annotations only declare readOnlyHint and openWorldHint; the description adds real behavioral context beyond them: newest-first ordering, an implicit 90-day default window, filer names withheld for individuals (a privacy behavior an agent could otherwise misread as missing data), and 'no interpretation of intentions; ratios as filed'. It stops short of stating result-count behavior or what happens when no filings match.

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 question, then dense supporting clauses with no filler sentences. Minor deduction for the dangling 'edinet_large_holding_reports' reference at the end, which reads as a truncated or misplaced pointer and slightly muddies an otherwise tight description.

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?

An output schema exists, so return values need not be described, and the description covers the ordering, default time window, privacy handling and the 'no interpretation' caveat. For a 4-parameter, read-only search tool this is nearly complete; only explicit sibling routing 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; the description earns above that by explaining that the same `issuer` argument is matched against issuerEdinetCode for large shareholding filings and subjectEdinetCode for tender offers — a semantic distinction the schema does not convey. The `kind` enum and `since`/`limit` semantics are left entirely to the schema.

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?

Opens with a specific verb+resource: 'Which large shareholding and tender offer filings name this Japanese issuer?' and names the two EDINET code fields used for matching (issuerEdinetCode vs subjectEdinetCode). It is clearly about issuer-side filings, which distinguishes it in spirit from the sibling edinet_large_holding_reports, but the trailing 'ratios as filed: edinet_large_holding_reports' fragment is ambiguous — it is unclear whether it points to a sibling tool, an output field, or a data source, so the sibling boundary is not stated crisply.

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 by the question framing and by the stated default of a 90-day window, so an agent can infer this is a 'filings about an issuer' lookup. However, there is no explicit when-to-use guidance, no exclusion, and no direct routing to the sibling edinet_large_holding_reports for the filer-side view.

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