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

Annotations already declare destructiveHint=true, readOnlyHint=false, idempotentHint=false and openWorldHint=true, so the safety profile is largely covered. The description adds a useful scoping fact that this mutates notification state only (not task status or payment), but it does not explain the acknowledged state being irreversible or what the response looks like. Adds some value, so a 3.

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, zero filler, with the core action front-loaded and the negative scoping clause second. Every sentence earns its place.

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-parameter mutation tool with no output schema, the description covers the core action and its blast radius. It is still missing how the cursor is obtained (presumably from list_notifications/wait_for_notifications) and whether repeated calls are safe, which an agent would need to call it confidently.

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% for the single 'through' parameter, so the schema alone gives no meaning beyond 'integer >= 0'. The description's word 'cursor' implies the value is a cursor mark obtained elsewhere, which is useful, but it never states the format, source, or inclusive/exclusive boundary of 'up to'.

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 gives a specific verb ('Mark ... as read') and a specific resource ('your notifications'), and scopes it to a cursor. The phrase 'up to an already-read cursor' is awkward and slightly ambiguous (does it mean the cursor must already be read?), which keeps it from a 5. It is still clearly distinguishable from list_notifications and wait_for_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?

It states what is NOT affected ('does not change task status or payment'), but never says when to call this versus list_notifications or wait_for_notifications, nor where the cursor value comes from. No positive usage context or alternative routing is provided.

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