ebay_get_order_earnings_by_id

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

Annotations provide only readOnlyHint, and the description adds substantial behavioral context beyond that: the required OAuth scope (and that it is not requested by default), seller-eligibility restrictions (approved US/CN/HK sellers with USD payouts), and a server limitation (no Digital Signatures for EU/UK Finances calls). This is exactly the kind of auth and constraint disclosure an agent needs before invoking.

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?

Front-loads the core purpose in the first sentence, then layers in scope/eligibility/signature caveats. All sentences are relevant and dense, though the caveats section is somewhat long for a single-sentence purpose.

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, the description compensates by naming the return fields (gross amount, expenses, refunds, net earnings), and it fully covers auth scope, eligibility, and known server limitations. An agent has everything needed to decide whether it can call this and what to expect.

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?

Schema description coverage is 100%, so both orderId and marketplaceId are already documented in the schema. The description only echoes 'for the orderId' and adds no new meaning about parameter format or the marketplaceId override — baseline 3 is appropriate.

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 earnings'), the resource ('for one order from the eBay Finances API'), and enumerates the returned fields (gross amount, expenses, refunds, net earnings). The 'for one order' scoping implicitly distinguishes it from the sibling summary/list variants, though no alternative is named explicitly.

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?

Provides clear context for when this is usable: it requires the optional sell.finances.earnings.read scope, which must be added to EBAY_OAUTH_SCOPES. It doesn't explicitly compare to ebay_get_order_earnings or ebay_get_order_earnings_summary, but the prerequisites are well stated.

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