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

Annotations only supply readOnlyHint=true, so the description carries most of the behavioral burden and does so: null semantics for fiscalPeriod/beforeAfterMarket/EPS, the consensus-vs-company-forecast distinction, JST date interpretation, and the >500-row pagination condition. It stops short of stating result ordering or exact row shape, which keeps it from a 5.

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 content order is sensible, leading with what the tool returns before describing fields, but the description is very long and restates essentially the same field definitions twice in English and Japanese, inflating length without adding information for a monolingual reader.

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 no output schema, the description usefully documents returned fields (fiscalPeriod, fiscalDate, beforeAfterMarket, actualEps, estimateEps) and their units, which is exactly what an agent needs to interpret rows. It omits only minor details like default sort order or the exact meaning of the surprise rate's denominator.

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 80%, and the description adds real meaning the schema lacks: from/to are interpreted in Japan time (JST), the offset is tied to the 'more rows exist' signal, and symbol is framed as an optional narrowing filter. The limit parameter is 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?

States a specific verb-like resource and scope: 'Upcoming and past earnings announcement dates for Japanese listed companies,' plus the payload (actual vs estimated EPS, surprise rate). It implicitly separates itself from the forecast sibling by noting 'the estimate is a market consensus, not the company forecast,' though it never names get_earnings_forecast directly.

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?

Gives concrete invocation guidance: pass symbol to narrow to one company, and re-call with the given offset when 'more rows exist.' However, there is no explicit when-to-use vs alternatives such as get_earnings_forecast, get_events_feed, or get_dividends_calendar, so the agent must infer routing.

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