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

Annotations already declare destructiveHint=true, idempotentHint=true and readOnlyHint=false, so the agent knows this mutates state and is safe to retry. The description adds useful scoping ('for the account behind this token'), which clarifies that the change is account-wide rather than per-post, but it does not say that disabling suppresses future mail irrecoverably or what the response contains.

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 short sentences with the action stated first and the motivation second. Nothing is redundant, though the second sentence is conversational and could have carried harder information instead of user-intent framing.

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 two-parameter toggle with full schema coverage and an output schema, the description covers the action, the scope and the intent. The remaining gap is the consequence of flipping a setting off, which for a destructiveHint=true tool would be worth one more clause.

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 both parameters are documented, including the cross-reference to get_notifications for valid `kind` values. The description adds only the phrase 'one kind of email', which slightly reinforces the single-value semantics but contributes no syntax or constraint detail beyond the schema.

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 gives a specific verb and resource: 'Switch one kind of email on or off for the account behind this token.' That is unambiguous and clearly distinct from read-only siblings like get_notifications, though it never names a sibling to contrast with.

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 supplies a loose motivation ('when the user wants less mail, or wants to hear about something again'), which hints at when to use it, but gives no explicit when-not conditions and never points to get_notifications as the prerequisite step for discovering valid values. Usage is implied rather than stated.

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