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

Annotations already declare readOnly/idempotent/non-destructive, but the description adds substantial context beyond them: nothing is deleted, the tool returns a confirmation_token valid for 10 minutes and bound to this specific sync, delete_sync requires that token, and the call costs no credits. These are exactly the behavioral facts an agent needs and cannot infer from annotations.

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?

The no-deletion guarantee and the token contract are front-loaded, and each sentence carries distinct information (preview contents, agent instruction, token lifecycle, eligibility, input source, cost). It is slightly dense and could be trimmed without loss, but nothing is filler.

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?

Given an output schema exists, return values need not be explained, yet the description still surfaces the one output an agent must handle (confirmation_token and its 10-minute validity). Combined with eligibility rules, input provenance, and the required confirm-then-delete flow, nothing needed to invoke it 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?

Schema coverage is 100% and the single ref parameter is documented in both schema and description. The description still adds value by constraining the ref's provenance ('from a current list_syncs result') and tying it to the target-calendar eligibility rule, though it adds no format details beyond the schema's example.

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 verb and resource ('Shows what deleting one of the user's own syncs would do, without deleting anything') and enumerates what the preview contains (connected calendars, count of copies removed). It is clearly distinguishable from its sibling delete_sync, which it explicitly names as the follow-up step.

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 explicit preconditions (only syncs whose target calendars are released for sync_target; syncs with another person are managed in the app), states the required input provenance ('Use a ref from a current list_syncs result'), and defines the downstream workflow by requiring the user to confirm and then call delete_sync with the token. Alternatives and exclusions are both covered.

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