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

Annotations already cover the safety profile (readOnlyHint=true, openWorldHint=false), so the bar is lower. The description still adds real behavioral value by disclosing what comes back: a day-by-day breakdown plus an iCalendar/webcal subscription URL intended to be handed to the user's calendar app, which the agent could not know from structured fields.

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 short sentences, front-loaded with the input and output scope, then the default, then the return artifact. The final clause ('to give the user for their calendar app') is slightly wordy but carries genuine invocation intent, so nothing is wasted.

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 only two parameters, no output schema and read-only annotations, the definition covers input format, default window, return shape and the calendar URL artifact. Minor gaps remain (behavior for unknown tickers, time zone of dates, pagination or size limits) but none would block a correct call.

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 100%, so baseline is 3, but the description earns an extra point by defining 'day' as any day within a Monday-to-Sunday week rather than a single day's data, which the schema's 'Any day in the week' only hints at. For holdings it merely restates the schema's ticker/CIK/FIGI list.

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 names a concrete resource set (ex-date, record date, payment date, effective date) scoped to a holder's tickers/CIKs/FIGIs over a one-week window, which is far more specific than the name alone. It implicitly separates itself from list_corporate_actions by being per-holding and calendar-week-scoped, but it never names the sibling it is not, so an agent must infer the boundary.

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?

'For a list of holdings ... in one week' plus 'this week by default' establishes the context of use, and the calendar-URL clause hints at the user-facing scenario. However, there is no explicit when-not guidance and no routing statement versus list_corporate_actions, get_corporate_action or token_corporate_actions, so the agent has to guess which corporate-action tool applies.

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