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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds real domain semantics beyond that: what 'holidays' means (events marked free, closes days only via rules.js daysOff) and the out-of-band dependency on Google Calendar for shared calendars. This is substantive behavioral context.

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?

Front-loaded with the primary scope, then the caveat about shared calendars last. It is dense but each clause carries information about returned fields. The nested parenthetical about holidays and rules.js is harder to parse than necessary, slightly hurting structure.

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 burden of explaining return fields and does so comprehensively, plus a dependency caveat. Annotations cover the safety profile. The only gap is not clarifying its relationship to get_calendar_refs.

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?

Zero parameters, so there is nothing for the description to compensate for; baseline 4 applies. The schema is empty and the description correctly focuses on return semantics instead.

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 states a specific resource and scope ("Every calendar across all connections") and enumerates the fields returned (id, name, access role, rules.js participation, holiday status, stdlib ref). An agent knows exactly what set and shape of data this returns. It does not, however, distinguish itself from the close sibling get_calendar_refs, which likely overlaps.

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?

Usage is only implied: it lists all calendars with no stated condition for choosing it over get_calendar_refs or list_connections. The one piece of guidance given — a shared calendar must be added in Google Calendar by its owner first — is a useful troubleshooting prerequisite rather than a when-to-use rule.

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