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

With no annotations, the description carries the disclosure burden. It makes clear this is a server-side aggregation rather than a raw fetch, implies read-only behavior through 'aggregate,' and clarifies the date-range default. It doesn't mention auth or rate implications, but for a simple summary tool the behavior is adequately transparent.

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 tight sentences lead with the core action and metric list, then give the essential date behavior and efficiency tip. There is no filler or repetition of schema details.

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 lists the output metrics and explains date-range semantics, which is sufficient for a simple read-only aggregation with no output schema. The only minor gap is ambiguous behavior when exactly one date is omitted.

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 schema already documents both parameters at 100% coverage, so the baseline is 3. The description adds the important rule that omitting both dates returns all-time performance, which is not derivable from the schema alone.

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 ('aggregate') and resource ('performance over a date range'), and enumerates the exact metrics included. It clearly distinguishes itself from raw trade fetching, and the rollup framing differentiates it from breakdown-style siblings.

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?

It explicitly directs the agent to 'Use this instead of fetching trades and adding them up,' naming the alternative and the reason. It also explains the all-time behavior when both dates are omitted, though it doesn't specify when breakdown siblings should be preferred.

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