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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, and closed-world, so the safety profile is fully covered. The description adds only the scope detail ('broadcast channels') and the subscription-flag behavior of the optional parameter — modest extra context, no disclosure on return shape or pagination.

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 with no wasted words and the core action front-loaded. It is arguably too terse given the undocumented parameter and absent usage guidance, but structure and sizing are appropriate.

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, read-only, zero-required-parameter list tool this is close to adequate, and the annotations carry the safety story. However, with no output schema, the description does not say what a listed channel contains or how the agent_id default resolves, so an agent must guess at those details.

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 0% for the single optional agent_id parameter, so the description must compensate. It explains the parameter's effect ('this agent's subscription flag') and that it is optional, but does not name agent_id explicitly or say whether omitting it defaults to the calling agent, leaving a real ambiguity.

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 verb and resource: 'List broadcast channels.' The scope word 'broadcast' narrows it beyond a generic channel list, and the parenthetical clarifies what the optional flag adds. It does not explicitly contrast with siblings like subscribe_channel or publish_channel, but the resource framing is clear enough to route 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?

There is no statement of when to call this versus subscribe_channel, unsubscribe_channel, or publish_channel, nor any prerequisite or exclusion. The parenthetical only implies that passing agent_id reveals a subscription flag; it gives no guidance on when that variant is appropriate.

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