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

Annotations give idempotentHint=true and destructiveHint=false, so safety/idempotency is covered. The description adds real value beyond that: it discloses the return value ('count of members that were updated'), the feature dependency (requires Notification Center), and the 404 conditions (feature disabled, batch missing, or belongs to another recipient/team). It does not restate the annotation hints, and there is no contradiction.

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?

Front-loaded with the core action, then filter semantics, then channel recording, then return/auth behavior. Every sentence carries information, though the sentence on filtering rationale ('Narrowing matters when...') is somewhat verbose and could be tighter. Overall efficient for the amount of conditional behavior it must convey.

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 6-parameter mutation with no output schema and low schema coverage, the description covers what an agent needs: scope of effect, filter behavior, mutual exclusivity, return count, feature gating, and 404 failure modes. Nothing material is missing 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 only 33% (only id and team_id have descriptions), so the description must compensate and largely does: it explains types as narrowing member types, severity as exact vs minSeverity as threshold and mutually exclusive, and openedFrom as recording the read channel applied to every updated member. team_id semantics are left to the schema, which is acceptable.

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+resource+scope: 'Mark every unread live member of a notification batch as read for the authenticated user.' Distinguishes clearly from siblings like markNotificationRead (singular) and markAllNotificationsRead (no batch scoping) by emphasizing batch-membership and the 'live/unread' qualifier.

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?

Explicitly explains when narrowing applies: 'Narrowing matters when the batch card was rendered under a filter: the rows marked read should be the rows the card counted.' It documents mutually-exclusive parameters (severity vs minSeverity) and states omitting filters marks everything. This is conditional guidance an agent could not infer from the schema.

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