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

Annotations already declare readOnly/idempotent/openWorld, so the description's real contribution is the payment model: $0.005 USDC per successful call via x402, plus an equivalent HTTPS endpoint. That is genuinely decision-relevant context an agent would otherwise lack; return shape is still unstated.

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?

Front-loaded with the core purpose in one dense clause, followed by short sentences for read-only, price, and the alternate URL. 'Read-only' duplicates the annotation, a minor wasted clause, but nothing else is padding.

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 should say what a call returns (token rows with mint, symbol, amount, UI balance order), and it does not. Cost and endpoint are covered well, but the response shape is left for the agent to discover.

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 all four parameters (address, limit, include_zero, include_token2022) are already documented, including Token-2022 behavior. The description adds no syntax or default detail beyond the schema, 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?

States a specific verb+resource: SOL and SPL (classic + Token-2022) balances for a Solana wallet address via public RPC. This clearly separates it from evm_balance or solana_tx, though it never names a sibling explicitly.

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?

Usage is only implied: the agent can infer this is for Solana addresses, and the mention of alternative endpoint (HTTPS) plus chain scoping helps. There is no explicit when-to-use / when-not vs evm_balance, wallet_risk_basic, or sol_token_meta.

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