get_deliverability_stats

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

No annotations are provided, so the description carries the full burden. It discloses the metrics and percentages returned but does not mention whether the operation is read-only, any authentication requirements, or potential side effects. Behavioral traits like data aggregation scope (e.g., across all inboxes vs. filtered) are implied but not explicitly stated.

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: three sentences plus a structured Args section. The purpose is stated first, followed by additional detail and usage guidance. There is no redundant information. The Args section is clearly formatted but could be slightly more integrated with the prose.

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?

Given the tool has 3 optional parameters and an output schema exists, the description adequately covers the tool's purpose, key metrics, and parameter guidance. It does not describe the return format, but that is handled by the output schema. The description lacks details on data range behavior (e.g., exact meaning of '24h') but is otherwise sufficient.

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 0% description coverage, but the description adds meaningful detail for all three parameters: inbox_id is 'recommended', domain_id is a filter, and period specifies allowed values ('24h', '7d', '30d') with a default. This goes well beyond the schema's type-only info, making the parameters understandable.

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 the tool retrieves email deliverability metrics (sent, delivered, bounced, complained, failed) and calculates percentages like bounce rate, complaint rate, and delivery rate. The verb 'Get' and the resource 'deliverability_stats' are specific. However, it does not differentiate from the sibling tool 'get_delivery_events', which may also provide event-level data.

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 advises using the tool 'to monitor sender reputation and identify deliverability issues,' providing a clear use case. However, it does not mention when not to use it or suggest alternatives, such as 'get_delivery_events' for more granular event data. The guidance is implied rather than explicit.

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