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

Beyond the readOnly/idempotent annotations, it discloses genuine behavioral traits: absence returns null, an alias marker with no balances avoids double-counting, unified accounts can hold funds in spot so zero native_perp is not empty, DEX margin accounts must not be summed with native_perp, and failed DEX reads surface via failed_dexes with meta.quality='partial'. These are non-obvious data-integrity semantics the agent would otherwise get wrong.

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 core scope is front-loaded in the first clause, but the remainder is a dense run-on of nested parentheticals mixing wallet taxonomy, field definitions, and error states. Since there is no output schema the content largely earns its place, but the structure makes it hard to scan.

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 carries the full burden of explaining return shape and it does so thoroughly: wallet entities, per-wallet native_perp/spot/hip3_perp fields, collateral_token, and partial-failure indicators. An agent can correctly interpret and act on the response from this text alone.

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?

Zero parameters yields a baseline of 4, and the description reinforces that identity is derived from the API key rather than supplied, which is meaningful for a parameterless tool. No further param detail is needed or possible.

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 and resource (account balances) and immediately pins the scope to the API key's own account, explicitly excluding an address input. That clause distinguishes it from address-oriented siblings such as get_wallets without needing to name them.

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 'YOUR ... no address input, identity comes from the key' phrasing implicitly tells the agent when this tool applies rather than an address-based one, and '(Requires api:read.)' flags a prerequisite. But there is no explicit routing against get_wallets, get_holdings, or get_portfolio_performance, so the when-to-use rule must be inferred.

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