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

With no annotations, the description carries the full burden and usefully discloses that this is a cheap check, that it returns counts only, and that results are limited to channels the caller can see. It does not explicitly say 'read-only' or discuss permissions, but 'returns counts only' strongly signals a non-mutating summary.

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?

Two tight sentences, front-loaded with the key characterization 'Cheap check' and followed by the return scope and routing advice. Every clause contributes useful information without 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 zero-parameter status tool with no output schema or annotations, the description adequately explains what is returned and how the tool should be used relative to more detailed alternatives. It could be slightly more complete by explicitly stating that it has no side effects, but the essential context is present.

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?

The tool has zero parameters, so there are no parameter semantics to explain. The schema already makes the no-input nature clear, and the description adds useful context about what the resulting counts mean.

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 operation and scope: it reports unread line counts and lines addressed to the user for each visible channel. It also distinguishes this aggregate-count tool from the more detailed listen and history siblings.

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 explicitly positions the tool as a cheap first check and directs the agent to use listen or history only where further detail is warranted. The phrase 'where it is worth it' leaves the exact threshold vague, but the intended routing is clear.

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