Subscribe to a channel

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

With no annotations, the description carries the full burden and delivers meaningful lifecycle semantics: a channel exists only while it has a subscriber, the subscription persists until unsubscribe, and each subscriber is routed separately. It omits behavior for repeat subscribes (idempotency), validation failures, or max channel limits.

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?

Three tight sentences with the core action front-loaded and the send_message routing hint appended for practical use. The final sentence about per-subscriber routing is slightly tangential but earns its place by clarifying delivery semantics.

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 one-parameter tool with no annotations and no output schema, the description covers lifecycle, interaction with send_message, and termination via unsubscribe. It leaves the return value and duplicate-subscribe behavior unspecified, but nothing critical to invocation 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?

Schema description coverage is 100% and the single `channel` param is fully documented with format constraints in the schema itself. The description only repeats the "#deploys" example, adding no syntax or constraint detail beyond the schema, so the baseline 3 applies.

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?

Specific verb-plus-resource ("Join a channel such as "#deploys"") with an inline example, and it clearly frames the tool as the inverse of unsubscribe by stating the subscription "lasts until you unsubscribe." An agent can distinguish this from send_message, broadcast, or unsubscribe without opening a 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?

It explains the mechanism for using the subscription (post with send_message by setting `to` to "#deploys") and when the relationship ends (on unsubscribe), which routes the agent to the right siblings. It stops short of explicit when-not-to-use or failure/duplicate-subscribe conditions.

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