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

Goes well beyond the annotations (which only supply idempotentHint/destructiveHint flags) by explaining what idempotency means concretely (returns alreadyRead=true without re-writing), the authorization scope (caller can only act on their own notifications), and the 404-on-miss behavior chosen to avoid leaking other users' ids.

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 tight sentences, front-loaded with the core action, then idempotency, then auth/404 semantics, then routing guidance. No sentence is 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-param mutation with no output schema, the description covers the return signal (alreadyRead=true), the failure mode (404), auth boundary, and alternatives — everything needed to invoke it correctly.

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?

Single parameter with 100% schema description coverage, so the schema already documents notificationId fully. The description adds no format, id-shape, or lookup guidance beyond it; baseline 3 is appropriate.

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 ('Flip a single notification's read flag to true') and explicitly scopes to one notification, distinguishing it from the bulk and dismiss siblings named in the same sentence. An agent can select it without opening the schema.

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?

Names two alternatives directionally: 'PREFER `mark_all_notifications_read` for bulk, `dismiss_notification` to remove entirely.' The condition that selects each alternative is stated, so routing is unambiguous.

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