Set the default channel

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

The annotations already declare this is a non-read-only, idempotent, non-destructive, closed-world mutation, and the description is consistent with that. It adds real value by disclosing the side effect's scope — it changes the fallback for any later tool call that omits a channel. It does not say whether the setting persists across sessions or what happens when the referenced channel is disconnected.

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 sentence, front-loaded with the action, and every clause earns its place by defining the default's effect. There is no filler or restatement of the title.

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 setter with full schema coverage and annotations covering the safety profile, this is nearly complete. The only material gap is the absence of failure conditions, such as what occurs when the supplied channel is not connected.

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 coverage is 100%, with the single 'channel' parameter documented as accepting an ID, @handle, or name, so the baseline is 3. The description adds one qualifier — the channel must already be connected — but offers no format hints or error behavior beyond the schema.

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 action and resource: choosing which connected channel serves as the default. It also explains what 'default' means operationally (the channel used when a tool call omits one), which is more informative than the title alone. It does not distinguish itself from connect_channel or list_channels by name, so sibling routing is left to the agent.

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 rather than stated: an agent can infer it should call this when it wants subsequent channel-less calls to target a specific account. There is no explicit 'use this instead of X' guidance, no prerequisite that the channel must first be connected, and no note on what happens if the named channel is not connected.

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