ENS name resolver

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

No annotations exist, so the description carries the full burden. It discloses a key behavioral trait: the tool is paid, with a specific cost and automatic payment from the user's wallet. However, it does not describe return formatting, error cases (e.g., unresolved names), or other side effects beyond payment. The cost disclosure adds value, but coverage is incomplete for a tool with no output schema.

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 two sentences: one stating the core purpose, one disclosing the payment model. It is front-loaded with the primary functionality and wastes no words. The payment warning is relevant and necessary for a paid tool, so every sentence earns its place.

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?

The tool is simple (one parameter, no output schema), and the description covers purpose and cost. However, it omits details about the return value structure and behavior when a lookup fails (e.g., unregistered name or address without reverse record). Given the low complexity, this is a minor gap, so the description is mostly 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?

Schema description coverage is 100% for the single 'query' parameter, which fully explains valid inputs ('ENS name (vitalik.eth) or address (0x...).'). The tool description adds no further parameter detail, so it does not improve on the schema. Baseline 3 is appropriate because the schema already provides complete semantics.

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 tool's function: 'Resolve an ENS name to an address, or an address back to its ENS name.' It uses a specific verb ('resolve'), names the resource (ENS), and describes bidirectional behavior. This distinguishes it from all sibling tools, which are focused on defi, chain, and wallet data, none overlapping with ENS resolution.

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 implies when to use the tool (when needing ENS resolution) but does not explicitly discuss alternatives or when not to use it. However, sibling tools are all in different domains (defi, wallet, chain metrics), so there's no ambiguity about which tool to choose. The absence of explicit exclusions is a minor gap, but the context is clear.

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