Mark chat as read

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

The description claims idempotency ('Idempotent: calling it again on an already-read chat is safe'), but annotations set 'idempotentHint' to false, creating a direct contradiction. As per instructions, this warrants a score of 1.

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 three sentences that efficiently convey purpose, side effects, idempotency, and prerequisites. Every sentence adds value, and the information is front-loaded, making it easy for an agent to quickly understand the tool's behavior.

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 action with no output schema and 4 parameters, the description covers the essential aspects: purpose, side effects (no notification), idempotency, and source of required parameter. It does not mention error handling or return values, but the action is straightforward and likely returns a status. With openWorldHint true, some behaviors may be unknown, but the description is reasonably 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 100%, so baseline is 3. The description adds value by clarifying the prerequisite for 'chat_id' (from messenger_get_chats_v2), but the other parameters are already well-documented in the schema. Thus, no significant additional meaning is provided.

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 the tool 'marks unread messages as read', using a specific verb ('marks') and resource ('chat'). It distinguishes itself from sibling tools like 'messenger_get_chats_v2' and 'messenger_delete_message' by focusing solely on the read-marking action, leaving no ambiguity about its function.

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 provides clear context: it informs that the action does not notify the other party and is not visible to them, and states idempotency. It also specifies a prerequisite ('Requires chat_id from messenger_get_chats_v2'). While it does not explicitly list alternatives or when not to use it, the context is sufficient for correct invocation.

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