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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered. The description adds genuinely new behavior: UTC day boundaries, a hard 1-92 day window, optional single-account or single-campaign scoping, and — importantly with no output schema — the exact metrics returned including error aggregation.

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 sentence, front-loaded with a `[read]` marker and the resource, then scope, then the returned metrics. Every clause carries information; nothing is redundant with the schema or annotations.

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 usefully enumerates the returned aggregates, and with 5 optional params it explains their selection role and the days bound. The only real gap is the id-vs-uuid interaction and whether filters combine, which matters for a tool whose entire parameter surface is optional selectors.

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 coverage is 0% (only bare titles like 'Days' and 'Sms Account Id'), so the description must carry the load, and it does: it gives the valid range 1-92 for `days`, states the days are UTC, and explains that the four account/campaign params are optional alternative selectors accepting an id or a uuid. It stops short of saying whether an id and a uuid may be combined or which wins.

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+resource (send-log summary report) with its scope (last `days`, UTC) and the metrics produced (sent/failed/skipped, success rate, billed segments, per-day counts, top provider errors). It is clearly distinguishable from list_sms_messages or get_sms_campaign in kind, but it never names a sibling, so the agent must infer the boundary itself.

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 aggregation framing implies 'use this when you want totals over a period rather than individual messages', and the optional account/campaign filters imply drill-down usage. However, there is no explicit when-to-use vs when-not statement and no pointer to the sibling that lists raw messages or the one that returns campaign configuration.

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