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

Beyond the annotations (which only say non-read-only, non-destructive), it discloses that only read state changes, the notification is retained, deletion is not offered, and that omission has a broad bulk effect. It does not address whether read state can be reverted or which permissions are needed, so not a full 5, but it meaningfully exceeds the annotation coverage.

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 sentences, front-loaded with the primary behavior and scope, then the caution, then the alternative routing. No redundant restatement of the title or name.

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-optional-parameter mutation with no output schema and existing annotations, the description covers scope, side effects, the destructive-ish bulk case, and sibling alternatives. Nothing an agent needs to call it safely is missing.

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 100%, so baseline would be 3; the description adds the semantic consequence of omitting notificationId (acts on all, clears badge), which is the key decision the parameter drives. It does not restate the id source, which the schema already covers.

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 ('mark read') and resource ('notification'), plus the dual scope (one vs. all) in the first clause. It names the sibling tools it is not (conversation_update, conversation_mark_all_read), so an agent can route correctly without opening a schema.

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 gives the condition for the all-notifications path ('if notificationId is omitted'), warns to confirm first because it clears the whole badge, and redirects inbox-thread cases to conversation_update / conversation_mark_all_read. Both when-to-use and alternatives are stated.

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