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

Annotations only say readOnlyHint=false; the description adds meaningful behavior beyond that: the operation is two-phase, returning a preview until confirm is true. It also discloses the side effect (unread count cleared). Missing is whether the change is reversible or scoped per user.

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 compact clauses with the primary action front-loaded and the gating caveat second. No filler, though the parenthetical could be phrased more tightly.

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 small mutation tool with no output schema and only a readOnlyHint annotation, the description covers the action and the confirm gate but leaves open what scopeId refers to, what the preview returns, and whether the read state is per-user or org-wide.

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 coverage is 67% and the schema already documents confirm and scopeType (with enum meanings). The description reinforces the confirm semantics but adds nothing about scopeId, which is undocumented in both places and leaves the key identifier ambiguous.

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 community as read') plus the concrete effect ('clears its unread count'), which distinguishes it from notification-marking siblings like mark_notifications_read. It does not name an alternative 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?

The parenthetical 'confirm-gated: previews until confirm: true' gives a clear operational instruction on how to actually execute, but there is no guidance on when to prefer this over related tools (list_my_communities, get_community_feed) or on preconditions.

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