Katzilla MCP

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, covering safety and idempotency. The description adds valuable behavioral context beyond annotations: it discloses the data source (Etherscan with terms reference), update frequency (real-time), and detailed return format (Katzilla envelope with quality scores and citation details including SHA-256 hash for audit). This enriches the agent's understanding of reliability and output structure.

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 highly concise and well-structured: it front-loads the core purpose in the first sentence, followed by supporting details (chain support, source, updates, return format) in a logical flow. Every sentence adds value without redundancy, making it efficient for an agent to parse and understand.

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's moderate complexity (2 parameters), rich annotations (covering read-only, non-destructive, idempotent, open-world traits), and the presence of an output schema (implied by the detailed return format description), the description is complete. It adequately explains the tool's purpose, behavior, and output without needing to reiterate structured data, providing all necessary context for effective agent use.

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 (address and chainId) well-documented in the schema, including patterns, defaults, and examples. The description adds minimal parameter semantics beyond the schema, only implying that chain ID enables multi-chain support. Since the schema carries the heavy lifting, the baseline score of 3 is appropriate, as the description does not significantly 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 specific action ('Get the ETH balance'), target resource ('Ethereum address'), and method ('using Etherscan'), with explicit mention of multi-chain support via chain ID. It distinguishes itself from sibling tools like crypto__etherscan-gas, crypto__etherscan-price, and crypto__etherscan-txlist by focusing solely on balance retrieval rather than gas fees, prices, or transaction lists.

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 clear context for usage: it specifies when to use this tool (to get ETH balance of an Ethereum address) and mentions support for multiple EVM chains via chain ID. However, it does not explicitly state when NOT to use it or name alternatives (e.g., other balance-checking tools), though the sibling list shows related Etherscan tools for different purposes.

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