ack_message

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

The annotation only provides destructiveHint=false, so the description carries the burden of explaining the tool's side effect. It does so well: it sets readAt, stops the message surfacing as unacked, is idempotent, and returns 404 for invalid IDs. No contradiction exists, though it stops short of discussing any broader state or rate-limit implications.

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 slightly longer than strictly necessary, but every sentence adds actionable information: purpose, exclusivity vs reading/listing, idempotence, and error behavior. The core how-to is front-loaded and the extra details support reliable calling.

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 single-parameter ack operation with no output schema, this description is complete. It tells the agent what the effect is, confirms repeated calls are harmless, gives the error condition, and notes the ID provenance. No essential behavioral information is missing.

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?

The schema description fully covers the only parameter, messageId, including where the ID originates. The description repeats that same source rather than adding new semantic detail, but because schema coverage is 100%, the parameter is already well documented and no further compensation is needed.

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 action ('Acknowledge a message by id'), the resource ('message'), and the effect ('sets it read so it stops surfacing as unacked'). It also distinguishes this tool from message-reading/list operations by emphasizing that it is the only thing that sets readAt.

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?

It explicitly tells the agent when to use this tool: after getting message IDs from list_messages or infrastructure_status, when intentionally marking a message as read. It also clarifies when not to expect side effects via idempotence, and what happens with a nonexistent ID. This gives clear usage context without assuming alternatives.

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