eth_call

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

With no annotations provided, the description carries the full burden for behavioral disclosure. It explicitly states the tool is 'read-only' and returns 'raw result', which clearly conveys the non-mutating behavior and output format. It could add details about potential errors or block context but remains transparent enough for an agent familiar with Ethereum.

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 a single, well-structured sentence that conveys all essential information without redundancy. Every word serves a purpose, making it efficient for an AI agent to parse.

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?

Given the tool has 4 parameters, no output schema, and no annotations, the description adequately covers the core behavior (read-only, raw result). However, it does not specify the return format in detail or mention potential pitfalls like gas estimation, which could be useful for an agent. Still, for a standard RPC call, it is sufficiently 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 input schema has 100% coverage with descriptions for all parameters (to, data, from, chain). The tool description adds value by clarifying the call is 'read-only' and returns 'raw result', which helps the agent understand the nature of the data parameter as 'ABI-encoded calldata' and the expected output. This goes beyond what the schema alone provides.

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 verb 'Execute' and the resource 'contract call', specifies it is 'read-only' (eth_call), and indicates the return type 'raw result'. This distinguishes it from sibling tools like get_balance or get_transaction_receipt, which have different purposes.

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 identifies that this tool is for read-only contract calls, implying it should be used when no state mutation is required. However, it does not explicitly exclude other scenarios or provide alternatives, leaving some ambiguity compared to siblings like rpc_call.

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