Get SMS account totals

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

Annotations already declare readOnly, idempotent, non-destructive and openWorld, so safety is covered. The description adds genuine interpretive context beyond that: what the numbers represent (sent/received message counts plus device counts) and what they are not (monthly plan quota), which prevents an agent from misreading the result.

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?

Two short sentences, both load-bearing: the first defines the returned data, the second rules out a plausible misreading. Nothing is padded or redundant.

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?

For a no-param, no-output-schema aggregate tool this is nearly complete — it says what categories of totals come back and what they are not. The one remaining ambiguity is the time window the totals cover (lifetime vs. current period), which the description leaves unstated.

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 there is nothing for the description to disambiguate; the baseline for a no-param tool applies. The description correctly implies account-level scoping without needing input.

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 ('Get') and a concrete resource ('sent/received message and device totals'), which an agent can distinguish from the sibling list_* tools that return individual items rather than aggregates. It doesn't explicitly name a sibling, but the aggregate-vs-listing distinction is clear from the wording.

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?

Usage is implied rather than stated: an agent can infer this is the tool for a summary/overview after seeing the list_* siblings. The line 'These totals are not the monthly plan quota' provides a useful negative disambiguation against quota-type data, but there is no explicit when-to-use or when-not-to-use statement.

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