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

With no annotations, the description carries the full behavioral burden. It usefully discloses the decoded output fields and the per-call x402 price on Base, but it does not clarify read-only guarantees, chain defaults, failure behavior, or limits such as only decoding static arguments. It also advertises a calldata-plus-address input mode that is not represented in the schema.

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?

The description is three efficient sentences and is front-loaded with the core operation and return values. The use case and price follow in a logical order with no wasted text.

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?

There is no output schema, so the description correctly explains the return shape: selector, known signatures, and decoded static arguments. However, the input-mode mismatch with the schema and the lack of chain/default behavior details leave meaningful gaps for correct invocation.

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 high, so the baseline would be 3. However, the description says the tool accepts "raw calldata plus a contract address" while the schema only defines optional hash and chain, and requires hash. This introduces nonexistent parameters and omits useful semantics for chain.

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?

The description states a specific verb and resource: "Decode an EVM transaction" and explains the exact return content (selector, known signatures, decoded static arguments). It is clear enough to separate decoding from sibling tools like evm_tx, but it does not explicitly name or contrast any sibling.

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?

It gives a clear use case: "Use it to explain what a transaction does before signing or reporting it." That helps an agent decide when this tool is appropriate, but it does not state when not to use it or name alternatives such as evm_tx or evm_receipt.

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