set_etherscan_api_key

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

Annotations indicate idempotentHint=true and destructiveHint=false. Description adds that the key is stored in process memory only (no persistence), with guidance on saving across restarts. Also notes that pasting a URL is rejected to prevent prompt injection, enhancing transparency. No contradictions.

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?

Well-structured with clear sections (purpose, input format, where to get, persistence, agent behavior). Every sentence is informative without redundancy. Front-loaded with primary use case and key 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 single-parameter tool with no output schema, the description covers all necessary context: purpose, usage trigger, security (rejecting URLs), persistence behavior, and how to obtain the key. No gaps remain.

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 covers the single parameter with description. Tool description adds value by specifying the exact format (34-char alphanumeric), providing an example, and stating that URLs are rejected. Also includes 'WHERE TO GET ONE' guidance. Since schema coverage is high, baseline is 3, but additional semantics justify a 4.

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?

Clearly states the tool sets an Etherscan V2 API key for runtime use, specifies the exact purpose (EVM transaction-history, allowance-enumeration, tx-explanation reads), and distinguishes from sibling tools like set_helius_api_key by naming the service and scope across 5 EVM chains.

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 tells when to use the tool ('when the user pastes a key in chat, call this tool immediately') and provides context on precedence over env var and userConfig. Includes instructions for persistence and where to get a key, but lacks explicit 'when-not-to-use' scenarios.

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