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

Annotations are all false and uninformative, so the description carries the burden. It adds concrete behavioral context: updates arrive on a specific WebSocket endpoint and can be filtered by sending a JSON payload. It does not disclose subscription lifecycle, unsubscribe semantics, or authentication details, but it does usefully describe the core runtime behavior.

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?

One dense sentence that front-loads the core action and then provides the essential endpoint/filter detail. No filler or repetition.

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 subscription tool with no output schema, the description covers the key invocation context: what to subscribe to, where updates arrive, and how to filter. It could be more complete about cancellation and delivery modes, but it is adequate for correct invocation.

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 the schema already documents target_kind, target, and delivery. The description adds a useful detail about the WebSocket filter payload, but it does not clarify the 'dm' delivery option or how thread subscriptions map to the feed.

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?

States a specific action ('Subscribe to a channel or thread') and the delivery mechanism (WebSocket feed). This clearly distinguishes board_subscribe from read/search siblings like board_read_thread and board_search.

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: if an agent wants real-time updates on a channel or thread, this is the tool to invoke. However, it does not explicitly contrast with alternatives, mention when not to use it, or explain whether to prefer board_read_post/board_read_thread for one-off reads.

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