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

Annotations already declare readOnlyHint=true, so safety is covered; the description adds genuinely new behavioral facts — results are a capped teaser subset, not the complete dataset, and the response includes an app link to the full calendar. It stops short of quantifying the cap or describing ordering/pagination.

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, front-loaded sentences with the resource and scope first and the limitation second. The trailing 'Read-only.' repeats the readOnlyHint annotation and does not strictly earn its place, but the rest is tight.

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 return-value burden and does so partially: it says the response is a capped teaser plus an app link. For a zero-required-param read tool this is largely sufficient, though cap size and ordering are unstated.

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% and the single enum parameter already documents all four values and its default ('defaults to earnings'). The description restates the same event types without adding format, combination, or filtering semantics beyond the schema, so the baseline of 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 verb and resource ('Get upcoming market events') and enumerates the four event types covered, plus the scope restriction to the Returnolio-covered universe. No sibling tool (screening, portfolio, scoring) overlaps a calendar endpoint, so an agent can route here unambiguously.

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 gives a clear when-to-use context ('teaser list, capped') and implicitly a when-not-to-use alternative: the full filterable calendar with history lives in the app, and the response carries a link to it. It does not name any sibling tool as an alternative, so it stops short of full explicit routing.

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