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

No annotations are provided, so the description must disclose behavioral traits itself. It reveals that the tool performs a read operation ('Retrieves') and returns aggregated metrics, but it does not mention permissions, rate limits, pagination, or any side effects. The read-only nature is inferable from the verb but not explicitly confirmed.

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 a single sentence with no filler, front-loading the key metrics. Every word contributes to the purpose, making it highly efficient.

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 explains the core output categories (volume, delivery rates, status breakdowns), which partially compensates for the missing output schema. However, it does not specify how these are structured (e.g., individual statuses vs. aggregates) or any defaults/limitations, leaving some ambiguity for an agent.

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?

Schema description coverage is 100%, so each parameter is already documented. The description's mention of a date range adds little beyond the schema's startDate/endDate descriptions; the parenthetical examples (today, yesterday, last 7 days) are mild additions but not critical.

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 states a clear action ('Retrieves...') and resource ('message volume, delivery rates, and status breakdowns'), which immediately distinguishes it from sibling tools like get_inbox_messages that retrieve raw messages. The specific metrics listed make the tool's purpose unmistakable.

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 implies usage for date-range analysis ('for a specific date range') but provides no explicit guidance on when to use this tool versus alternatives such as get_inbox_messages or get_campaign_performance. No exclusion criteria or alternative tool names are mentioned.

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