channel_read_ack

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

With no annotations provided, the description carries the behavioral burden and it does disclose key traits: the operation is idempotent and monotonic, and passing a time earlier than or equal to the current watermark is a no-op returning advanced=false. This is exactly the kind of behavioral context an agent needs. It stops short of describing permissions/authorization or any side effects beyond the watermark update.

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 tight sentences, purpose front-loaded in the first clause and the idempotency/monotonicity behavior stated second. Every sentence earns its place with zero padding.

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?

An output schema exists, so return values (advanced=false) need not be explained at length, and the 100%-covered parameter schema is thorough. The description covers purpose and the core idempotency behavior. Only minor gaps remain around authorization/who may ack as an actor, but the essential information for a correct call is present.

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% and the schema already documents all four parameters, including the critical warning against passing 'now' with pagination. The description only reinforces the meaning of last_read_at (传入时间) implicitly. Baseline 3 is appropriate when the schema does the heavy lifting.

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 states a specific verb and resource: advancing a channel's read watermark (已读水位) to the last message actually read and clearing the corresponding unread. This is clearly distinct from sibling read tools (channel_read, channel_unread, channel_mentions), which the parameter descriptions further tie it to. An agent can identify this as the ack/advance-watermark action without opening the 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?

Usage is implied — use this after you have actually read messages, to advance the watermark. It does not explicitly say when to prefer it over a hypothetical alternative, nor state prerequisites (e.g., that you must have read the messages first), though the last_read_at parameter notes reinforce correct usage. Implied context only.

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