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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered. The description adds that these are 'announced' (forward-looking) dates, which is mild behavioral context, but it discloses nothing about rate limits, auth, freshness, or coverage windows beyond what annotations provide.

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?

Two tightly written sentences: the resource and returned fields come first, followed by illustrative queries. No filler and nothing repeated from structured fields.

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?

There is no output schema, so the description carries the burden of describing returns — and it does, naming cash dividend per share, stock dividend ratio and subscription terms. Combined with the schema's parameter docs, an agent has enough to call and interpret this tool correctly.

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 schema already documents both parameters (limit range/default and symbol matching by code, abbreviation or Chinese name). The description adds no syntax or semantic detail beyond the schema, so the baseline 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?

States a specific resource and scope: 'Announced ex-dividend and ex-rights dates for TWSE-listed securities', and enumerates the returned fields (cash dividend per share, stock dividend ratio, subscription terms). This is clearly distinguishable from siblings like taiwan_stock_quote or taiwan_stock_valuation, which cover price/valuation rather than corporate-action calendars.

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 example queries ('when does 2330 go ex-dividend', 'which Taiwanese stocks go ex-dividend this month', 'what is the dividend on 2412') give clear, concrete triggers for when to reach for this tool. It lacks explicit when-not guidance or named alternative tools, so it falls short of a 5.

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