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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false, covering the safety profile. The description adds value beyond annotations by disclosing the cost per call ($0.001 USDC), supported chains, and that it is byte-identical to a specific GET endpoint. It also explains the internal logic (reading EIP-1967 slots next to implementation()), which is useful. 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?

The description is about three sentences and front-loads the core purpose (EIP-1967 slots) before practical details. It is efficient with no redundant filler, though the 'byte-identical to GET' sentence could be considered extra but is informative. Overall, it is appropriately sized and well-structured.

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 simplicity, annotations covering safety, an output schema present, and 100% parameter coverage, the description is complete enough. It covers cost, chains, and the rationale for use. It does not detail return format, but that is handled by the output schema. Minor gaps like error handling are not critical 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 coverage is 100% for both parameters, so the baseline is 3. The description adds a concrete example with a real chain and address (base and 0x8335...), which clarifies usage. It also repeats the chain list, reinforcing valid values. This extra context justifies 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?

The description clearly states the tool checks if an address is a proxy by reading EIP-1967 slots and identifies what is behind it (implementation). It distinguishes itself from sibling bytecode-checking tools by explaining that bytecode-size checks alone understate upgrade impact. The verb 'read' and resource 'EIP-1967 slots' make the operation 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 explains why this tool is needed (bytecode-size checks understate what an upgrade can change), implying it should be used when proxy status matters. It lists supported chains and cost, providing practical context. However, it does not explicitly name alternatives or state when not to use it, though the rationale gives clear guidance.

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