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

Annotations already communicate read-only, idempotent, non-destructive behavior, so the description correctly focuses on non-obvious output semantics: negative cost_basis means net profit withdrawn, and cost_basis/current_value/cost_diff are in USD while per-token fields are in raw units. This goes beyond annotations and prevents misinterpretation of return values.

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?

The description is front-loaded with the core action and then provides compact, high-value details about return semantics and units. Every sentence earns its place, and there is no redundant or filler content.

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?

Given the rich annotations, complete input schema, and presence of an output schema, the description covers everything needed for correct invocation: the lifetime scope, sign interpretation, and unit differences. No critical gaps are apparent.

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 input schema already documents both parameters, including chain_id's allowed values and default and account_address's meaning. The description adds no parameter-specific guidance, so with 100% schema coverage the baseline score of 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?

The description opens with a specific verb and resource: 'Get PnL (cost basis) and yield earned for an Arcadia account.' This clearly distinguishes the tool from siblings like read_account_history or read_account_info, which serve different purposes even though they also target accounts.

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 makes the tool's context clear: it is for retrieving lifetime PnL and yield for an Arcadia account. It does not explicitly name alternatives or exclusion criteria, but the scope is specific enough that an agent can infer when this tool is appropriate.

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