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

Annotations already cover the read-only, idempotent, non-destructive profile, so the bar is lower; the description still adds real value by naming the required 'earnings:read' permission and enumerating the distinct ledger states (Pending, Available, transferred, bank receipt). It does not describe pagination or ordering of the ledger, but the interpretive constraints are exactly the kind of context annotations cannot express.

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: capability plus permission requirement first, then the interpretation constraints, then the hard exclusion. No filler, and the most load-bearing rule about not summing currencies lands before the payout disclaimer.

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 and no parameters, the description carries full burden for describing what comes back, and it does convey the important parts: the ledger states and the handling of unknown receipts. It stops short of indicating the shape or granularity of entries (per-transaction vs aggregated), which an agent would want before formatting results.

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 parameter semantics are trivially satisfied and the stated baseline of 4 applies. Nothing in the description conflicts with the empty schema, and the currency/receipt caveats relate to interpreting results rather than to inputs.

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?

Names a specific verb and resource: read the original rewards and cash ledger. The 'original...ledger' framing distinguishes it from derived siblings like evuun_get_rebates or evuun_preview_rebate_conversion, though it never names those siblings explicitly to sharpen the contrast.

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 states what must not be done with the results ('do not sum different currencies or turn unknown receipt into zero') and excludes the payout capability, which is genuinely useful scoping. But it never says when to prefer this over adjacent tools such as evuun_get_rebates or evuun_read_business_events, leaving the primary routing decision implied.

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