get_deliverability

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

With no annotations, the description carries the full burden, and 'best-effort' is a genuine disclosure that the metrics may be incomplete or approximate. It says nothing about auth requirements, rate limits, data freshness, or whether results are aggregated per-domain or per-send.

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?

A single tight sentence with the resource and window scope front-loaded and zero wasted words. Nothing is redundant and every phrase earns its place.

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?

No output schema or annotations exist, and the description does not indicate what metrics are returned or how they are broken down. For a simple one-parameter read tool this is adequate but leaves real gaps for an agent predicting the response.

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?

Only one optional parameter exists and its enum (7d/30d) is self-documenting in the schema; the description merely restates those two values. It does clarify that the window applies to 'recent sends', adding modest meaning, but no default or omission behavior is described.

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 verb ('Fetch') and resource ('deliverability metrics') with scope ('recent sends'). An agent can tell it apart from list_emails/get_email, though the description never names a sibling or explicitly contrasts with them.

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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives. The only implicit cue is 'recent sends', which hints at the reporting use case but does not tell the agent when this tool is the right choice.

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