Etherscan MCP

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool's function but lacks critical details: it doesn't specify if this is a read-only operation, what permissions or authentication might be required, potential rate limits, error conditions, or the format of the returned balance. For a tool with no annotation coverage, this leaves significant gaps in understanding its behavior.

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, efficient sentence that directly states the tool's purpose without any unnecessary words. It's front-loaded with the core action and resource, making it easy to parse quickly. Every part of the sentence contributes to understanding the tool's function, achieving optimal conciseness.

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 complexity of a blockchain tool with three parameters and no annotations or output schema, the description is incomplete. It doesn't address behavioral aspects like safety, performance, or error handling, nor does it explain what the output will look like (e.g., numeric balance, units). For a tool in this context, more detail is needed to fully guide usage.

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% description coverage, with clear documentation for all three parameters (chain_id, token_address, address). The description adds no additional semantic context beyond what the schema provides, such as examples or constraints. Since the schema does the heavy lifting, the baseline score of 3 is appropriate, but the description doesn't enhance parameter understanding.

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 action ('Get the balance') and the target resource ('a specific token for a specific address'), making the purpose immediately understandable. It distinguishes this tool from siblings like 'get_token_holders' or 'get_total_supply' by focusing on balance retrieval rather than holder lists or supply metrics. However, it doesn't explicitly mention the blockchain context, which is implied but could be more specific.

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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, such as needing valid addresses or chain IDs, or compare it to sibling tools like 'get_token_holders' for different use cases. Without any context on when or why to choose this tool, users must infer usage from the purpose alone.

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