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

readOnlyHint=true is complemented by rich context the annotation can't carry: sendReady is a fully-ramped flag and NOT a send gate, top-level sendReady is an AND across all mailboxes, vendorReputationScore/vendorPlacementRate are vendor-reported and null when unmeasured, vendor-pool warmup is feed-invisible, and reading never marks messages read. This preempts real misinterpretation traps.

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?

Dense and fairly long, but front-loaded with purpose and each sentence disambiguates a specific semantic trap (dual sendReady flags, null vendor fields, read-only messages). It could be broken into clearer groupings, but little is wasted.

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?

With no output schema, the description carries the full burden of describing returns and does so by naming the return shape plus the semantics of ambiguous flags and severity sources. Nothing an agent needs to call or interpret this correctly 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 takes zero parameters, so there is nothing to document; the baseline of 4 applies. The description instead explains the meaning of returned fields, which is more valuable here than parameter detail.

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 resource and scope: warmup + provisioning progress per mailbox, and enumerates the returned shape. It explicitly differentiates from siblings by naming account/metrics for rollups and setup_infrastructure for next actions, so an agent can tell it apart without opening schemas.

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 routes the agent to alternatives ('Use account/metrics for rollups', 'see setup_infrastructure', severities via list_messages) and clarifies that this tool is for per-mailbox ramp capacity. It never states explicit when-not-to-use conditions, but the context is clear.

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