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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuine context beyond them: results are time-ordered and each notification entry carries content, audience and delivery data, and the feed mixes in festival/holiday/app dates rather than only notifications. It stops short of stating pagination, maximum entries, or how the holiday data is sourced.

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 sentences, front-loaded with the core idea ('the calendar of what is coming') and followed by the scope rule. The parenthetical '(with their content, audience and delivery)' is dense but earns its place by describing return payload; nothing is redundant.

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 two-parameter read-only query with no output schema, the description does the work of sketching the return shape (notifications with content/audience/delivery plus calendar events, in time order) and the default breadth. Only the absence of ordering-field or volume details keeps it from being fully complete.

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%: 'days' (1–60, default 30) and 'appId' are both fully documented in the schema. The description only restates the appId omission behavior, adding no syntax or format detail beyond what is already structured, 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?

The name 'coming_up' is opaque on its own, but the description immediately specifies the resource: a time-ordered calendar of scheduled/sending notifications plus festivals, holidays and app dates. An agent knows exactly what it retrieves, though it never names the sibling it differs from (e.g. list_notifications) to make the distinction airtight.

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?

It gives one useful scoping rule — 'Without appId it covers every app the key can use' — which signals the default is broad. However, it offers no explicit when-to-use guidance versus list_notifications or get_notification, so an agent must infer that this tool is the calendar/forward-looking view while those are the historical or single-item views.

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