Email overview

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

Annotations already declare readOnlyHint=true and openWorldHint=false, and 'Read only.' merely restates that. The real added value is the disclosure of what the response contains — including the meaning of the custom 'firstHeard' field and its categories — which the agent would otherwise have to discover empirically, since there is no output schema.

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?

Information density is high and the routing sentence lands last, but the body is one very long run-on sentence enumerating fields, and the opening 'Read only.' duplicates the annotation rather than front-loading anything new. It is efficient in word count but weakly structured.

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?

With no output schema, the description carries the burden of explaining return values, and it does so field by field, including the segment shape (id, name, approximate confirmed count) and the firstHeard categories. Only minor gaps remain, such as whether counts are live or cached and what an unconfigured sender state looks like.

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 tool takes zero parameters, so the baseline of 4 applies. No parameter semantics are needed and the description correctly spends its words on return content instead.

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 names a specific resource — the workspace email overview — and enumerates exactly what it reports: email on/off, sending open, sender readiness, confirmed-subscriber counts, monthly quota, saved segments, and the firstHeard breakdown. That makes it clearly distinguishable from siblings like postfjord_get_analytics or postfjord_list_campaigns. It stops short of a crisp verb-first statement of purpose, leading instead with a return-value inventory.

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 closing sentence, 'Start here before drafting or scheduling an email,' gives explicit positioning in the workflow and implies the drafting/scheduling siblings that follow. There are no stated exclusions or conditions under which to skip it, so it is clear context rather than a full when/when-not matrix.

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