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

Annotations already declare readOnlyHint=false, destructiveHint=false, and idempotentHint=true, so the safety profile is known. The description adds the one-vs-all behavior, but this is partly redundant with the schema's parameter description. It does not describe return values or side effects, so it adds limited context beyond structured data.

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 two sentences, front-loaded with the action, and every word earns its place. It is concise and clearly structured.

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 one-parameter mutation tool with no output schema and good annotations (idempotent, non-destructive), the description covers the essential usage. The one-vs-all behavior is fully specified, and no additional context is necessary for correct invocation.

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%; the parameter description in the schema already states 'The notification to mark as read. Omit to mark every notification read.' The tool description essentially repeats this, so it adds no additional semantic meaning beyond the schema.

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 clearly states the action ('Mark notifications as read') and specifies the resource. It also differentiates the two modes (single vs all) with 'Pass notification_id for one; omit it to mark them all.' This distinguishes it from sibling get_notifications which retrieves 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 provides explicit usage instructions for the parameter, but does not name alternatives or explicitly state when not to use this tool. It implies the context (marking notifications read) and gives a clear conditional rule for single vs all, which is sufficient guidance for selection.

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