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

Annotations already declare the mutation and idempotency profile, but the description adds useful behavioral context: ownership scoping ('owned notification'), not-found behavior for 'Missing or foreign IDs,' and 'result:null on success.' It does not explain the destructiveHint or why setting seen is treated as destructive, but it meaningfully supplements the annotations.

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?

Three short sentences, front-loaded with the operation and scope, followed by error and return behavior. Every sentence carries information an agent can act on.

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 mutation with annotations covering safety and an output schema covering returns, the description is largely complete: it covers ownership, missing/foreign ID handling, and success signaling. The only notable gap is the semantics of the seen boolean.

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 compensate. It adds ownership meaning to notificationId, but it does not explain the required boolean 'seen' parameter or clarify that it can set the notification unseen as well as seen, leaving one of two parameters semantically thin.

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 and resource: 'Set seen on one owned notification identified by notificationId.' The word 'one' implicitly distinguishes it from bulk siblings such as updateNotificationsSeen and updateAllNotificationsSeen, though those alternatives are not named 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?

The description implies single-notification usage through 'one owned notification,' which contrasts with bulk update tools. However, it never explicitly states when to choose this over updateNotificationsSeen or updateAllNotificationsSeen, leaving the routing to inference.

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