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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces 'reads or computes only and changes nothing'. It goes further with non-annotation behavior: malformed addresses return 400 and are uncharged, failed calls are free, but repeat calls are billed and idempotentHint=false is effectively explained. Pricing, error handling and billing model are all disclosed.

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 operation and limits, then use-case routing, then error/billing details — a sensible priority order for a single dense paragraph. It is somewhat crammed with pricing and payment-mechanism detail that could be trimmed, but every sentence carries actionable information.

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, yet the description names the returned fields (direction, counterparty, amount, transaction), the ordering (newest first) and the 50-result cap. Combined with the charge model and failure semantics, an agent has everything needed to call it correctly and interpret the result.

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 the schema already documents token ticker-or-contract, block range with default, and the address format. The description mostly restates those (1-2,000 blocks, default 1,000, default USDC) and adds only the example address and the 'in and out' framing, so it does not add much beyond the structured fields.

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 — list a wallet's recent ERC-20 transfers on Sonic — plus scope (in and out, sourcing both directions), default token, block window, ordering and result cap. An agent can distinguish it from sonic_token_balance without opening either 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?

Gives explicit use cases ('confirm a payment arrived or see what was sent') and names the alternative plus the condition that selects it ('for the current balance use sonic_token_balance'). That is a complete routing rule.

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