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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is partly covered; the description adds the merge/partial-write behavior, which is real value beyond the annotations. What it never explains is why the operation is flagged destructive — whether changes apply immediately, whether anything is lost, or how to undo via reset_my_notification_preferences.

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, zero filler, with the scope stated first and the partial-update rule second. Nothing is redundant with the title and every clause carries information an agent needs.

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 six-parameter tool with deep nesting, the schema does the heavy lifting and the description correctly covers who is affected and the merge semantics. It falls short on the destructive/idempotency implications and on routing to the reset or read siblings, which an agent would want before mutating preferences.

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 description coverage is 100% and the nested objects (kinds, quiet, digest, timeZone, waitingMinutes, emailDelayMinutes) are each documented in the schema itself. The description adds only the global partial-update rule, not per-parameter meaning, so the baseline 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?

States a specific verb ("Change") plus the exact resource and scope: the signed-in person's own notification preferences. That self-scoping implicitly separates it from update_team_notification_defaults and get_notification_preferences, but it never names those siblings explicitly.

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?

"Anything left out stays" communicates that this is a partial/patch update, which is genuine usage guidance for calling it. However, there is no statement about when to prefer it over get_notification_preferences (read first) or reset_my_notification_preferences (revert), so the agent must infer the workflow.

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