EVM MCP Server

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the agent knows this is a safe, repeatable read operation. The description adds valuable context beyond annotations: the API key requirement, network support (30+ EVM networks), and the verification constraint. No contradiction with annotations.

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?

Four concise sentences, each earning its place: purpose, usage context, prerequisites, and scope. Front-loaded with the core action, no wasted words, and structured logically from what to why to constraints.

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 read-only tool with good annotations and full schema coverage, the description provides excellent contextual completeness: purpose, usage guidelines, prerequisites, and scope. The only minor gap is lack of output details (no output schema), but the description implies ABI return, which is reasonable for this tool.

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 both parameters well-documented in the schema. The description doesn't add specific parameter semantics beyond what the schema provides, but it reinforces the contractAddress focus and network flexibility. Baseline 3 is appropriate when the schema does the heavy lifting.

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 ('fetch') and resource ('contract's full ABI'), specifies the source ('from Etherscan/block explorers'), and distinguishes it from siblings by focusing on ABI retrieval rather than balances, transactions, or contract interactions. It's specific and unambiguous.

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 states when to use ('to understand verified contracts before interacting') and provides context about prerequisites ('Requires ETHERSCAN_API_KEY') and limitations ('Works best with verified contracts on block explorers'). It clearly differentiates this read-only tool from write operations like write_contract.

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