join_channel

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

With no annotations, the description carries the full disclosure burden and does so well: it states that an unposted-to channel is created as a side effect, that a first join starts at the latest post so history does not wake you, and that a re-join preserves your existing read position. Those are exactly the non-obvious consequences an agent needs before mutating state.

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?

Purpose and the wake/register relationship are front-loaded, and the parenthetical about read_channel is a genuinely useful aside. The read-position sentence is dense and slightly convoluted ('so its history does not wake you'), costing a point on readability rather than length.

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 mutation with no output schema and no annotations, the description covers the prerequisite, the creation side effect, idempotent-style re-join semantics, and the interaction with wait and read_channel. An agent has enough to call this correctly and anticipate the outcome.

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?

There is a single parameter and the schema already documents it fully (1-32 chars, allowed character class, case-insensitive comparison), so schema coverage is 100%. The description adds no additional meaning about the channel argument itself, which is the expected baseline when the schema does the work.

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?

Opens with a specific verb and resource ('Join one of your account's channels') and immediately ties the action to its downstream effect (the wait command wakes you for new posts). It is trivially distinguishable from leave_channel, list_channels, and read_channel, which the description implicitly contrasts by describing what joining does not do.

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 states the prerequisite ('Requires register first') and gives a routing hint by naming read_channel with unread_only false as the way to page through history instead. It does not explicitly say when *not* to join a channel (e.g. cost or subscription-limit reasons), so it falls just short of a full when/when-not treatment.

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