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

Annotations show readOnlyHint=false and destructiveHint=false already, so the mutation aspect is understood. The description adds the return value—'Confirmation with count of updated notifications'—which is useful, but it does not disclose behavior when both arguments are supplied or whether repeated marking is idempotent.

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 description is compact and front-loaded with the action. The Args and Returns lines are each necessary and directly useful, with no filler or repetition of schema types.

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 simple two-parameter tool with no output schema, the description covers the action, both operation modes, and the return shape. The only meaningful gap is the missing rule for what happens when both mark_all and notification_id are provided.

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%, so the description must carry parameter meaning. It does: notification_id targets a single notification)Skip, mark_all targets all. This covers the essential semantics, though the interaction between the two parameters is not explained.

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: 'Mark notifications as read.' It is unambiguous and distinct from siblings like delete_notification or get_unread_notification_count, clearly identifying a state-change operation on notifications.

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?

The description gives no contextual guidance about when to use this tool versus alternatives. It does not mention when to prefer mark_all over notification_id, nor does it exclude cases like deleting notifications or viewing unread counts.

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