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

Annotations already declare readOnlyHint=false and destructiveHint=false, but the description adds the caller-side authorization requirement ('requires write scope'), which the annotations do not convey and which materially affects whether an agent may call it. It stops short of describing partial-update behavior or what the response returns, but for a small mutation tool this is meaningful added context.

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 with the operation front-loaded and the permission requirement second; nothing is padded or redundant. It is close to minimal, though the example and the scope note could be slightly more tightly integrated.

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 two-parameter, non-destructive mutation with no output schema, the description covers what it does, an example of the primary use, and the auth requirement needed to succeed. Minor gaps remain around whether fields other than 'read' are updatable and what is returned, but these are small relative to the tool's simplicity.

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%, so the schema already documents both 'id' and 'read'. The description's 'mark as read' phrasing reinforces the meaning of the boolean but adds no format, defaulting, or unread/read toggle detail beyond what the schema states. 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 ('update a notification') and gives a concrete example of the operation ('mark as read'), which makes the tool's intent unambiguous. It does not explicitly contrast with the obvious sibling delete_notification, but the verb alone separates them.

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 parenthetical 'e.g., mark as read' implies the typical use case, and 'requires write scope' signals a precondition. There is no statement of when not to use it or which alternative to pick for other notification operations, so guidance is implied rather than explicit.

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