mark_messages_seen

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

Annotations already signal mutation (readOnlyHint=false), idempotence, and non-destructiveness. The description adds useful behavioral context by clarifying that read-only listing/fetching tools do not trigger the seen side effect, and by giving the real-world portal analogy. There is no contradiction with annotations.

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 convey the action, the behavioral context, and the sibling distinction with no wasted words. The core action is front-loaded before the explanatory analogy.

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?

The tool is simple, annotations cover safety and idempotence, and schema covers all parameters. The description gives enough context to select and invoke it correctly, though it does not describe return values or error behavior; this is minor for a low-complexity mutation tool with no output schema.

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 the parameters are already well documented in the schema, including where to obtain workspace_id and message_ids. The description itself adds no parameter-level meaning beyond the schema, which fits the baseline for high schema coverage.

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 uses a specific verb and resource ('Mark feed items as seen') and immediately differentiates from siblings by stating that list_messages and get_message never do this on their own. It is clear what the tool does and how it differs from related read tools.

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 description explains the portal's Activity tab behavior and explicitly warns that list_messages and get_message do not mark items as seen, which helps an agent know when this side effect is needed. It does not name an alternative tool to use instead, but the context is sufficient for selection.

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