todayVsYesterday

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

With no annotations, the description carries the behavioral disclosure burden. The verb 'Compare' strongly implies a read-only aggregation, and the listed metrics clarify what is computed; however, it does not state that no writes occur, how the day boundary is determined, or what the response shape is.

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, no filler, front-loads the action and scope. Every word contributes meaning.

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 parameterless comparison tool, the description is largely complete: it defines the time range and the metrics. Minor missing context such as timezone handling or return formatting is not critical for invocation, though it would improve clarity in the absence of an output schema.

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?

There are zero parameters and 100% schema coverage, so the description does not need to document parameters. It adds useful context by naming the exact metrics included in the comparison.

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 action ('Compare'), a precise resource scope (transaction count, volume, and success/failure rates), and an explicit timeframe (today vs. yesterday). It does not explicitly distinguish itself from sibling analytics tools like dailySummary or weeklyAnalytics, but the 'vs yesterday' frame makes the comparison intent 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 date comparison is clear, so an agent can infer when this tool applies, but no alternative tools are mentioned and there is no explicit when-to-use/when-not-to-use guidance. The usage context is 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.