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

Annotations already declare readOnlyHint=false, idempotentHint=true and destructiveHint=false, so safety is largely covered. The description adds genuinely new context by disclosing that omitting ids mutates every notification in bulk, which is the main risk an agent needs to know.

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?

One short sentence, front-loaded with the action and ending on the default-scope caveat. Nothing redundant and no 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?

For a one-parameter idempotent mutation with annotations covering safety and no output schema, the description supplies the essential scope semantics. Minor gaps remain around whether unread-count/return data exists and whether ids come from list_notifications, but nothing blocking.

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 0% and the sole parameter is optional, so the description carries the burden of explaining what happens when it is absent ('all of them without ids'). It does that clearly; only the id format (string ids from list_notifications) is left implicit.

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 ('Marks ... as read') and resource ('notifications'), and adds the scope distinction that no ids means all notifications. It is clearly distinct from the read-only sibling list_notifications, though it never names that sibling 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?

Usage is implied by the operation itself and the 'or all of them without ids' clause signals the bulk case, but there is no explicit when-to-use/when-not guidance or reference to alternatives such as list_notifications for discovering ids first.

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