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

The annotations declare destructiveHint=true and idempotentHint=false, and the description adds real value with the ownership error behavior and the required API-key scope (notifications:write). However, it is silent on the destructive/non-idempotent claims — an agent gets no hint that the state change is characterized as destructive or that repeating the call is not guaranteed safe. Not contradictory, but only partially compensating.

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. The ownership constraint and auth scope are front-loaded after the core action.

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 single-parameter mutation with a full input schema, the description covers the action, the authorization requirement, the failure mode, and the required scope. The one remaining gap is any statement about reversibility or the meaning of the destructive annotation.

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 account, workspace, and identifier are already fully documented in the input schema. The description only reinforces that identifier refers to a notification the caller owns; 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 ('Mark a single notification as read'), and 'a single notification' implicitly distinguishes it from the sibling pm_mark_all_notifications_read. It does not name the sibling explicitly, so it stops short of a 5.

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 gives one hard precondition (owner-only, error otherwise), which is useful, but never says when to choose this over pm_mark_all_notifications_read or how it relates to pm_list_notifications. Usage is implied rather than routed.

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