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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description reinforces this with 'Read-only.' It adds valuable behavioral context beyond annotations: earnings 'settle non-custodially to your withdrawal address on release,' clarifying that no action is needed for payouts. This enriches the agent's understanding without contradicting the structured hints.

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 sentences with no filler. The first sentence is front-loaded with the purpose, the second packs the return scope and the key read-only/non-custodial behavior. Every clause adds distinct information — earnings composition, pending/in-flight state, claim-later rewards, payout address, and settlement semantics.

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 zero-argument read-only tool, the description is complete: it enumerates all return categories, clarifies the read-only nature, and explains the settlement behavior. No output schema exists, so the description carries the full burden of return-value disclosure and does so thoroughly. Nothing an agent needs to decide invocation is missing.

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 has zero parameters and the schema already documents that the owner is derived from the authenticated principal (100% schema coverage). The description adds no parameter details because none are needed; per the baseline for zero-parameter tools, this is appropriate. It correctly focuses on what the tool returns rather than input handling.

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 opens with a specific verb+resource pair: 'Check how much I have earned and what is pending.' It then itemizes the exact scope (lifetime USDC, in-flight pending, unclaimed rewards, payout balance, buyer spend, reputation), which clearly distinguishes it from other account/balance tools in the sibling set. No ambiguity about what the tool does.

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 description implies the usage context — checking seller earnings, pending amounts, and related payout info — but it does not explicitly state when to prefer this tool over siblings or mention any alternatives/exclusions. The context is clear enough for a well-scoped read-only query, but the routing guidance is left implicit.

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