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

With no annotations, the description carries the full burden of behavioral disclosure. It states the main behavior and clarifies that no new chat message is sent, which is useful. However, it omits details such as authentication requirements, idempotency, or effects on unread state beyond marking read.

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?

The description is two short sentences with no filler. The main action is front-loaded, and the clarifying exclusion earns its place by preventing confusion with messaging tools.

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 and the core behavior is stated, but with no annotations, no output schema, and no parameter documentation, the description leaves token semantics and response/error behavior unspecified. It is minimally adequate but not fully complete.

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 0%, and the description does not mention token or message_ids at all. The agent is left to infer the meaning of the token parameter and the expected format of message IDs solely from their names and types.

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 clearly states a specific action ('Mark messages as read') on a clear resource ('messages'). The clause 'Does not send a new chat message' explicitly distinguishes it from messaging tools like send_message and send_and_wait.

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 the core purpose and an important negative constraint ('Does not send a new chat message'), which helps prevent misuse. However, it does not name alternative tools or specify contextual conditions for when to choose ack_messages over other message-related operations.

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