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

Annotations already cover read-only/idempotent/non-destructive/closed-world, and the description still adds real behavioral context: no event titles returned, zero credit cost, null id/name for calendars outside the shared set rather than hiding the sync, shared_with_person syncs never name the other person's calendar, and what an empty list actually means.

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 core purpose and return semantics, then the ref contract, then sibling routing. Dense but largely earns its length; the final paragraph reads a little like a tool directory and the dashboard URL could be trimmed, keeping it short of a 5.

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 an output schema present, the description needn't explain return values, yet it covers the non-obvious edge cases (empty list, null calendar id, shared_with_person anonymity, two-way single entry) and the downstream ref usage. Nothing an agent needs to call this correctly is missing.

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 the baseline is 4. The description still adds semantic value by explaining that the returned short refs are positional inputs to other tools, which is the closest thing to a parameter contract 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+resource (lists the user's own calendar syncs) and immediately scopes it: 'the user's own', with the clarification that a two-way sync is one entry, not two. An agent can distinguish this from list_calendars and from the create/preview sync tools without opening a schema.

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?

Explicitly routes the agent: the short ref feeds diagnose_sync and set_sync_paused, pausing/resuming goes to set_sync_paused, creating goes to preview_sync/create_sync, deleting to preview_delete_sync/delete_sync. It also states the condition for re-calling (positional refs, call again if syncs may have changed).

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