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

Annotations already cover read-only and non-destructive behavior. The description adds useful context beyond annotations: it limits the result to the active tenant, specifies what the snapshot contains, and defines a 2% suppression-rate threshold that should be surfaced as a warning. It does not detail the response format, but the stakes are low for a read-only, zero-parameter tool.

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 sentences with no filler: the first states what the tool returns, the second gives call conditions, and the third adds the actionable threshold. The useful information is front-loaded.

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 read-only snapshot with no output schema, the description fully covers what the agent needs: what the tool returns, when to call it, and how to interpret the result. Nothing essential 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?

The tool has zero parameters and no schema burden, so the baseline is 4. The description nevertheless communicates the data returned, which is all an agent needs to invoke the tool.

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 opens with a specific verb and resource: 'Get a deliverability health snapshot for the active tenant' and enumerates the returned breakdown (total suppressed emails, 30-day trend, reason breakdown). The scope is distinct from the sibling analytics and campaign tools, so an agent can identify this as the suppression/list-health tool without opening other definitions.

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 gives explicit when-to-use guidance: 'Call this when the user asks about list health, unsubscribe rates, or bounce issues.' It does not explicitly name alternative tools or state when not to use it, which keeps it just below a 5.

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