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

With no annotations, the description carries real weight: it discloses the per-call cost and payment model (x402), the chain-dependent asymmetry of what is returned (EVM returns only native + USDC, not all ERC-20s; Solana filters zero balances). It does not state error behavior, rate limits, or whether the call is read-only, which are minor omissions for a balance read.

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 compact clauses, front-loaded with the primary per-chain result and ending with the cost that gates invocation. Every sentence earns its place and there is no filler.

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?

No output schema exists, so the description is the only source of return-value semantics — it names which assets come back but not the response shape (amounts, decimals, USD valuation, ordering). Combined with no error/payment-failure guidance, it is adequate but leaves an agent guessing about the payload.

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% and all three parameters, including the enum and the paymentProof 402 flow, are already documented in schema. The description's chain-specific return contents add a little meaning to the `chain` enum, but the schema does the heavy lifting, so baseline 3 applies.

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?

It states precisely what the tool returns per chain (SOL + all non-zero SPL/Token-2022 on Solana; native + USDC on EVM), which is far more specific than a name restatement. It lacks an explicit verb phrase and does not name any sibling, but no sibling in the list overlaps with balance retrieval, so confusion risk is low.

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?

There is no 'use this when / not when' guidance and no alternatives are referenced, so the agent must infer the use case from the name and return contents. The cost disclosure ('0.003 USDC per call via x402') is the one decision-relevant hint, implying usage should be deliberate for a paid call.

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