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

Annotations already declare idempotentHint=true, destructiveHint=false and non-read-only, so the safety profile is covered. The description still adds a real behavioral fact beyond the structured data: the notification "drops out of the unread count," telling the agent the observable side effect on state.

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: the action and scope come first, the effect and a usage example follow. Every clause earns its place with 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 mutation with full schema coverage and safety annotations, the description covers purpose, trigger, and side effect adequately. It omits only edge behavior such as what happens when the notification is already read or an invalid UUID is supplied.

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 single parameter is already documented as a 'Notification UUID — from list_notifications.' The description adds no format, provenance, or error semantics beyond the schema, so 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 (mark read) and resource (notification) plus the singular scope, which implicitly separates it from the sibling mark_all_notifications_read. It never names that sibling explicitly, so the differentiation is inferred rather than stated.

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?

"e.g. after relaying it to the user" gives a concrete trigger condition for when to call this. There are no explicit exclusions or a named alternative (mark_all_notifications_read) for bulk cases, so timing guidance is clear but alternatives are left to inference.

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