get_delivery_stats

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

With no annotations, the description carries the burden, and it discloses the data source (Mektup's Postfix delivery log), what the counts represent (real SMTP responses), and the aggregation scope. It does not mention permissionns, rate limits, or exact return formatting, but for a read-only stats tool the core behavioral semantics are transparent.

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?

One dense sentence that front-loads the core action and then adds the key provenance caveat; every clause earns its place and there is no filler.

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 exists, but the description effectively summarizes what the response will contain (counts of sent/deferred/boounced/unknown) and scopes it to a mailbox and time window. It is lightly light on output shape and edge cases, but nothing essential is missing for calling the tool correctly.

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?

Input schema coverage is 100%, so the schema already documents 'days' and 'mailbox' clearly; the description only restates the time-window and mailbox concepts without adding format, default, or constraint details. This meets the baseline but adds little beyond the schema.

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 opens with a specific verb and resource ('Aggregate delivery outcomes for a mailbox's outbound mail') and enumerates the exact count categories (sent/deferred/bounced/unknown). It also distinguishes the data provenance from a third-party tracking pixel, so an agent can tell it apart from unrelated stats/usage tools.

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 clearly states the context: use for outbound delivery outcomes over a time window, and clarifies that it reflects real SMTP responses from Postfix logs rather than pixel-based tracking. It does not explicitly name sibling tools or state when not to use it, but there is no close alternative among the listed siblings.

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