Get Global Email Statistics

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds no behavior beyond 'Retrieve', such as response shape, aggregation semantics, or potential size of results. It does not contradict the annotations, but it also does not add meaningful behavioral context beyond them.

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 direct sentence with no filler. It front-loads the verb and resource, and every word contributes to the meaning. It is appropriately concise for a straightforward read-only statistics tool.

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 tool is simple, the schema is complete, and annotations cover safety, so the description is minimally adequate for invoking the tool. However, there is no output schema and the description does not clarify what metrics are returned or how this relates to the many sibling statistics tools, leaving some ambiguity for an AI 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?

The input schema has 100% description coverage for all three parameters, including formats, defaults, and the enum for aggregated_by. The description adds no parameter-level detail, but the schema already carries the full semantic burden, so the baseline of 3 is appropriate.

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 uses a specific verb ('Retrieve') and a clear resource ('global email statistics for your SendGrid account'). It distinguishes from sibling stats tools through the word 'global', implying account-wide scope as opposed to per-browser, per-country, per-category, or per-subuser stats, but it does not explicitly compare against those alternatives.

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 phrase 'global email statistics' implies this tool is for account-wide aggregates rather than dimension-specific breakdowns, but the description never explicitly states when to use this tool versus siblings like get_stats_by_country, get_category_stats, or get_subuser_stats. Guidance is therefore implied rather than stated.

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