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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds valuable context beyond annotations: the use of external services (openchain.xyz, eth_abi), a cost of $0.001 USDC, and EVM-only limitation. It doesn't mention error handling or rate limits, but the added context is meaningful for a read-only 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?

The description is one concise sentence followed by two short fragments. It is front-loaded with the primary action, then includes scope and cost. Every word adds value; there is no redundancy.

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?

For a simple read-only tool with rich annotations and schema, the description covers the key points: what it does, external dependencies, cost, and output shape ('function name + typed parameters'). It doesn't describe failure modes, but the schema already captures the main error (solana 400). The description is sufficiently complete for an agent to use the tool 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 description coverage is 100%, with each parameter clearly documented (chain enum with solana returning 400, calldata_hex with prefix details, contract_address as optional/unused). The description adds no extra parameter-level information; baseline 3 is appropriate given the high schema coverage.

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 ('Decode'), resource ('raw EVM calldata'), and output ('function name + typed parameters'). It clearly distinguishes from sibling tools like decode_tx by focusing on calldata rather than full transactions, and explicitly notes EVM-only scope.

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?

The description implies usage (when you have raw calldata) and gives a constraint (EVM-only), but it does not explicitly mention when to avoid this tool or name alternatives such as decode_tx. No clear when-to-use vs when-not-to-use guidance is provided.

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