mark_messages_seen

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

Annotations already indicate a non-read-only, idempotent, non-destructive operation. The description adds valuable behavioral context beyond those hints by explaining that this is exactly what happens when the user opens the Activity tab, and by warning that the read tools do not trigger this side effect. This helps the agent understand the real-world implication of calling the tool.

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, purposeful sentences. The first explains the action and its real-world trigger; the second prevents a common misuse by disambiguating from the read siblings. Every sentence earns its place without redundancy.

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 simple mutation tool with strong annotations and full schema coverage, the description is nearly complete. It explains the side effect, the portal context, and the distinction from related reads. It does not describe the response, but there is no output schema, so that is acceptable. A small gap is that it doesn't mention idempotency consequences, but the annotation already covers that.

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?

Input schema coverage is 100%, with clear descriptions for workspace_id and message_ids, so the schema carries the parameter documentation burden. The description adds the useful notion of 'feed items' but does not substantively improve on the already-complete parameter descriptions.

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 ('Mark') and resource ('feed items as seen'), and explicitly clarifies the portal behavior it models. It also differentiates itself from sibling tools by stating that list_messages and get_message never perform this side effect on their own, making the tool's purpose unambiguous.

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 gives clear context for when this tool is appropriate: it mirrors opening the Activity tab and marks feed items as seen. It also tells the agent that the read-oriented siblings do not do this, which helps prevent incorrect assumptions, though it does not explicitly cover when not to use it or list alternative marking tools.

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