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

Annotations only say readOnly=false and destructiveHint=true; the description adds the crucial human-approval gate, idempotency semantics, dry_run reserving nothing, and operation_id polling via get_operation. This goes well beyond the annotation hints and matches the declared side-effectful nature.

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?

The description is compact, front-loaded with purpose, and every sentence contributes workflow, prerequisite, or dry-run behavior. The only minor issue is a dense middle that could be split for readability, but it is not padded.

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?

The two-step approval flow, idempotency, dry-run semantics, and operation_id polling are well covered. But with no output schema and several unexplained parameters (sender, brand_hint, prefer_prewarmed), the description leaves meaningful gaps an agent would need to resolve before invoking the tool confidently.

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 only 13%, so the description carries the burden; it does clarify dry_run, confirmation_token, idempotency_key, and approval_url meaningfully. However, it leaves sender, brand_hint, and prefer_prewarmed unexplained, and emails_per_week is only inferred from 'sending capacity.'

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?

Description opens with 'Provision warmed sending capacity (domains, mailboxes, DNS and warmup)' – a specific verb and resource that clearly separates it from campaign/lead tools like create_campaign or add_leads. The title 'Buy sending capacity' reinforces the action.

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?

Lays out the purchase flow explicitly: unconfirmed request → quote/token/approval_url → post-approval request with a stable idempotency_key. States the prerequisite 'Requires assets:purchase' and distinguishes dry_run as advisory-only. It doesn't name alternatives explicitly, but the unique provisioning purpose and sibling names make the when-to-use unambiguous.

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