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

Beyond the annotations, it discloses a range of behaviors an agent needs: 8 KB calldata cap, a revert producing HTTP 422 with the reason and no charge, pricing via x402 USDC or card key, first 25 calls free, and that repeats are charged (consistent with idempotentHint=false). This is unusually rich context for a paid call tool.

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 purpose, then usage, then mechanics, then pricing; every sentence carries information. Slight redundancy in restating that each call is charged after already quoting $0.01/call, and the pricing tail occupies more space than the core semantics.

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, and the description compensates by stating that the return is raw ABI-encoded data to be decoded with the function's ABI. With revert handling, size limits, cost model, and the optional sender parameter covered by the schema, an agent has what it needs to call this correctly.

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 the baseline is 3, but the description adds real meaning: it explains that 'data' is 4-byte selector plus ABI-encoded arguments, gives literal example values for 'to' and 'data', and notes the 8 KB limit. It does not cover the optional 'from' parameter, which the schema handles as msg.sender.

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 ('Read-only contract call on Sonic (eth_call)') plus what it returns (raw return data at the latest block, no transaction or gas). It also distinguishes itself from the many sonic_* siblings by positioning itself as the fallback for view functions that have no dedicated tool.

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?

Explicitly says when to use it ('read any view function that has no dedicated tool') and implicitly excludes cases covered by sonic_token_balance, sonic_balance, sonic_storage, etc. It adds the follow-up step (decode with the function's ABI) and a concrete worked example with selector 0x18160ddd for USDC totalSupply.

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