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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered. The description adds two genuine traits beyond that: results come from a day-by-day index of the EDINET document list, and withdrawn filings carry no content. The rest is largely a restatement of returned fields (which the output schema already carries), and 'our translation' / 'Facts only' are only vaguely informative.

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-loading the scope question is good, but the second half is a long comma-separated field inventory that duplicates the output schema and dilutes the useful behavioral notes. The closing 'Facts only.' is cryptic and does not clearly earn its place.

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 an output schema, 100% parameter coverage and read-only annotations, the definition supplies the remaining context an agent needs: the data provenance, the default 365-day window, and the withdrawn-filing caveat. Only minor items like pagination/limit behavior relative to the indexed range are left implicit.

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 description coverage is 100%, so all four parameters (code, limit, since, doc_type) are already documented with formats and defaults. The description adds the notion that code may target a company 'or other filer' and that the default window is 365 days, but contributes no syntax or format detail beyond the schema, 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 rhetorical question states a clear verb (submitted) and resource (EDINET documents filed by a given Japanese company or other filer), and names the source index explicitly. It is distinguishable from edinet_filing_relations and edinet_holdings_tender_offers in substance, but never names or contrasts those siblings, so an agent must infer the boundary.

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?

There is no explicit when-to-use or when-not-to-use guidance and no reference to the sibling tools (catalog, edinet_filing_relations, edinet_holdings_tender_offers). The 'last 365 days' framing implies a lookup use case, but the agent gets no routing rule for choosing this tool over the related EDINET tools.

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