get_deliverability_stats

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explains the metrics and rates returned, and recommends inbox_id filtering. However, it does not clarify aggregate scope when no filters are passed or mention read-only behavior explicitly, though the 'get' verb implies it. No contradiction with annotations (none exist).

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 concise and front-loaded with purpose. It has a clean structure with a purpose statement, a sentence on outputs, a usage context sentence, and an args list. Every sentence provides value without waste.

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 description sufficiently covers purpose, usage, and all parameters. An output schema exists, so return value details are encoded elsewhere. It could mention when to prefer get_delivery_events for individual events, but this is not critical for basic tool selection and invocation.

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 input schema has no descriptions (0% coverage), so the description fully compensates by explaining each parameter: 'inbox_id: Filter metrics by inbox (recommended)', 'domain_id: Filter metrics by domain', and 'period: Time period — "24h", "7d", "30d" (default: "7d")'. This adds meaning beyond the schema properties.

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 clearly states 'Get email deliverability metrics: sent, delivered, bounced, complained, failed' with a specific verb and resource. It also lists derived rates (bounce, complaint, delivery) and distinguishes itself from siblings like get_delivery_events (which fetches individual events) and get_suppressions (which manages suppressions), making the tool's purpose unambiguous.

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?

The description provides a clear use case: 'Use this to monitor sender reputation and identify deliverability issues.' It does not explicitly mention alternatives or when not to use the tool, but the context is sufficient for an agent to decide between this and related tools.

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