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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds genuinely new behavioral context: the default-to-today behavior and the 120-day forward horizon beyond which dividends are unannounced, which affects how results should be interpreted.

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?

A single dense sentence that front-loads the core content (what goes ex, on which date) before the field list and the date-window caveat. Every clause carries information, though the long enumeration makes it slightly heavy to scan.

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 carries the burden of describing returns and does so explicitly, listing all the fields a caller can expect. Combined with the default and forward-window caveats, an agent has everything needed to call and interpret it.

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 date format and the limit bounds; the baseline of 3 applies. The description reinforces the date default and the 120-day horizon but adds no syntax or constraint detail beyond 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?

Names a specific resource (every U.S.-listed dividend going ex) scoped to one date, and enumerates the returned fields (amount, pay date, yield, safety grade, change, last day to buy). This is clearly separable from siblings like get_dividend_raise_calendar or get_dividend_payers_by_month without opening a schema.

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 implies usage via 'Defaults to today; dates up to 120 days ahead include announced dividends', which tells the agent the useful date window. However, it never says when to pick this tool over the sibling dividend tools, so the routing guidance is left to inference.

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