Account Balance

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds the return structure (balances[] with fields) and the currency filter behavior, which is useful. However, it does not disclose details like pagination, rate limits, or what happens when no currencies match. With annotations covering the safety profile, a 3 is appropriate.

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 waste. The main purpose is front-loaded, followed by the return structure and the filter option. Every sentence earns its place.

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 read-only, idempotent tool with 100% schema coverage and no output schema, the description is quite complete. It states what the tool returns, the filter option, and the safety profile is covered by annotations. The only minor gap is not describing the exact shape of the balances[] array beyond field names, but that is acceptable given the description lists the fields.

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 parameters (_jq and currency) are already documented in the schema. The description adds a concrete example of currency values ('USD', 'HKD') and clarifies that omitting currency returns all currencies, which slightly enhances the schema. Baseline 3 is correct since the schema does the heavy lifting.

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 clearly states the tool's function: 'Get account cash balance and asset summary.' It specifies the resource (account balance) and the action (get), and it lists the return fields. It is distinguishable from siblings like stock_positions or fund_positions because it focuses on cash balance and asset summary, not positions.

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 provides a clear usage context: it is for retrieving account cash balance and asset summary, with an optional currency filter. It does not explicitly state when not to use it or name alternatives, but the context is clear enough for an agent to select it for balance-related queries. Sibling tools like stock_positions or fund_positions are position-focused, so the distinction is implicit.

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