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

Annotations already declare a safe, idempotent, closed-world read, so the bar is lower. The description adds real behavioral context beyond them: results are grouped by payer cadence and returned with 'Largest companies first', which tells the agent about ordering before it sets limit.

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?

Three sentences, front-loaded with the resource definition and ending with the useful ordering note. Every sentence carries content; only minor trimming would be possible.

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 3-param read tool with no output schema and full annotation coverage, the description covers scope, categorization, and sort order. It stops short of describing the returned fields or pagination, but nothing essential for correct invocation is missing.

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 67% with month and schedule documented in-schema. The description adds a little interpretation ('including off-cycle schedules' for quarterly, and the trailing-year window for month), but does not explain limit or how the categories interact with the schedule enum beyond what the schema states.

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+resource: 'U.S.-listed stocks that paid a dividend in a given calendar month over the last year,' and enumerates the payer categories. It is clearly distinguishable from calendar-style siblings like get_ex_dividend_calendar, but it never names an alternative to route between them.

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?

'Useful for building a portfolio that pays every month' gives implied usage context, but there is no explicit when-to-use vs when-not, no prerequisites, and no reference to the sibling dividend tools that cover overlapping queries.

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