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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds meaningful non-obvious behavior: the full set of returned sections and the security detail that 'the calendar key itself is never returned' — context an agent cannot get from the annotations or the empty schema.

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 what is returned, followed by the actionable 'call this first' instruction and a security caveat. It is dense but every clause carries information; the long enumeration in sentence one is the only mild readability cost.

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?

There is no output schema and no input schema, so the description effectively serves as the return-value documentation, listing the fields an agent will receive. Combined with the 'call first' usage cue and the key-not-returned note, an agent has everything needed to call it correctly.

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?

The tool takes zero parameters, so there is nothing for the description to document and the baseline is 4. The description does not introduce any parameter guidance, which is correct here.

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 ('The calendar this connection points at') and enumerates the returned facets: title, timezone, date settings, custom fields, sub-calendars, key permission, plan features. This clearly separates it from sibling tools like teamup_get_subcalendar, which would only cover one sub-calendar, and it even names the endpoint (GET /{calendarKey}/configuration).

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?

Gives explicit sequencing guidance: 'Call this first to learn the sub-calendar ids and the timezone,' which tells the agent both when to invoke it and what prerequisite knowledge it yields. It does not state when not to use it or name a direct alternative, so it falls short of the top band.

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