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

Annotations already declare readOnlyHint and openWorldHint, yet the description still adds real operational context: Jupiter as the pricing source, a 15-second cache window, a top-50 truncation limit, and a per-call price of $0.020 with the x402 payment rails (USDC on Base or Solana). What it omits is failure behavior and whether zero-balance mints are included, which keeps it below a 5.

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?

Three dense sentences with the capability stated first, then the pricing methodology and truncation limit, then caching and cost. No filler and no repetition of the title.

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 explaining the shape of the response (priced balances sorted by USD value, capped at 50) and the payment prerequisite. It stops short of covering error cases or what happens on an unpriced or empty wallet, but the essentials for calling it correctly are present.

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 coverage is 100%, so both the address pattern/example and the tx field are already documented in the schema. The description only touches the tx parameter obliquely by describing the x402 payment mechanism, adding no syntax or fallback detail beyond structured data.

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 pair: it returns a Solana wallet portfolio covering SOL plus all SPL/Token-2022 balances with USD pricing. The Solana scope cleanly separates it from the many evm_* siblings without the agent needing to open any schema.

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 Solana-only scope implicitly tells an agent when to pick this over evm_balance or evm_token_balance, but that routing is left to inference rather than stated. There is no explicit when-not-to-use guidance or named alternative.

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