prepare_transactions_evm

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

With no annotations provided, the description carries full responsibility for disclosure. It reveals that the tool returns the raw unsigned transaction hex and fee details, and it implies the operation has no on-chain side effects ('ready for signing'). It also adds credit cost details, which is useful context. It does not cover all potential behaviors (e.g., authentication, rate limits), but it covers the essential nature of the operation.

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 well-structured: it starts with a clear one-sentence overview, then lists the three actions with brief explanations, and finally includes credit information. It is concise enough for the complexity it covers, though the credit section could be trimmed if not essential, but it does contribute operational context.

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?

The tool has 12 parameters and no output schema, yet the description gives sufficient context: it names the three actions, describes the expected output (transaction hex and fee details), and outlines the follow-up steps for signing and broadcasting. It does not provide examples or error handling details, but for correct invocation it is reasonably complete.

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?

The schema provides descriptions for 100% of the parameters, including which actions they apply to. The tool description adds value by explaining what each action does, but it does not add meaning for individual parameters beyond the schema. Given the high schema coverage, this baseline of 3 is appropriate.

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 clearly states the tool's function: 'Build unsigned EVM transactions ready for signing.' It lists three specific actions (native transfer, ERC-20 transfer, NFT transfer), which distinguishes it from downstream signing and broadcasting tools. The mention of the prepare-sign-broadcast workflow further differentiates its 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 provides explicit guidance on when to use the tool: before signing locally via a tool like evm_sign, and before broadcasting via broadcast_signed_transaction. It gives a clear sequential workflow but does not explicitly state when not to use it or name alternative preparation tools, so it falls slightly short of a 5.

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