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

Annotations already declare the tool read-only and idempotent, and the description adds valuable behavior beyond that: it walks the daily filing lists rather than calling a company-search endpoint, returns results newest first, and requires an EDINET Subscription-Key. This gives an agent useful expectations about authentication and data source mechanics.

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 compact and front-loaded with the core purpose, then adds necessary mechanism, prerequisite, auth, and a clear example. Every sentence earns its place and there is no filler or repetition of schema details.

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 5-parameter tool with no output schema, the description plus schema covers input semantics, required auth, date-range constraints, sorting, and the identification prerequisite. It does not describe the return structure or potential error conditions, but those are not essential for a correct first call given the strong example and annotations.

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 the baseline is 3. The description adds value with a concrete invocation example using edinet_code, from, and to, and clarifies that edinet_code should come from edinet_search_filers. It also reinforces the 31-day range constraint and the auth requirement, making correct invocation easier.

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 uses a specific verb and resource: 'All EDINET filings by one Japanese company over a date range,' and immediately scopes it to a single filer with a 31-day limit and newest-first ordering. It also distinguishes itself from the related company-identification tool by naming edinet_search_filers, making the tool's role clear.

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 gives clear context for when to use this tool: after identifying the company with edinet_search_filers, and it explains why this approach is necessary because EDINET lacks a company-search endpoint. It does not explicitly contrast with edinet_list_filings, but the single-company filtering is strongly implied and the prerequisite workflow is explicit.

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