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

With no annotations, the description carries the full burden and does disclose useful traits: it is free, makes no paid call, and returns either decoded x402 payment requirements or the upstream result on a 200. However, the return behavior is ambiguously worded ('or the result'), and nothing is said about error/timeout handling or rate limits.

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?

Two sentences, front-loaded with the 'FREE' qualifier and the tool identity. No filler, though the second sentence is dense and slightly hard to parse.

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?

With no output schema, the description must explain returns, and it partially does (x402 payment requirements or upstream result). For a simple one-parameter tool this is mostly sufficient, but the ambiguous return wording and absent error behavior leave gaps.

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% and the single 'address' parameter is fully documented as a '0x EVM address' in the schema. The description's 'for an EVM address' merely restates that, adding no syntax or format detail, so the baseline 3 applies.

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?

States a specific verb+resource: a wallet checker for an EVM address returning agent-likeness, sybil flags, and FLAPJAX holding. It is clearly distinguishable from generic siblings like evm_balance or evm_tx, though jargon such as 'agent-likeness' and 'x402' is left unexplained.

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 says what the tool is but never states when to use it versus alternatives such as evm_balance or evm_token, nor any prerequisites beyond providing an address. The 'FREE' marker hints at a cost-based selection reason but no explicit guidance is given.

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