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

Annotations only declare readOnly/openWorld/idempotent; the description adds the behavior that actually matters here: a per-call price ($0.001 USDC on Base), the x402 payment mechanics on first-call failure, and the parallel HTTP endpoint. That is real context beyond structured fields.

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?

Front-loaded with scope and returned fields, then pricing/payment, then the HTTP mirror — a logical order with no filler. It is a single dense run-on paragraph, which costs a point on readability but not on information density.

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 carries the return-value burden itself and does so by naming every field including raw vs. decimal supply and EIP-1967/legacy OZ proxy slots with implementation and admin addresses. Combined with the payment flow, an agent has everything needed to call it and interpret the result.

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 50%: 'token' is documented and 'chain' is an enum that the description re-enumerates. It adds value by disclosing an out-of-schema parameter channel — params._meta['x402/payment'] — which the agent cannot learn from the schema, though it does not clarify address formatting beyond '0x'.

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 ('For a token contract on base, ethereum... : name, symbol, decimals, total supply, code size, owner(), proxy status') and enumerates the exact payload returned, which cleanly separates it from siblings like token_risk, token_balances and erc20_allowance.

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?

Usage context is clear: call this when you need ERC-20 metadata plus upgradeable-proxy detection on one of the eight listed chains, and it explains the payment retry path (unpaid call → PaymentRequired → retry with _meta['x402/payment']). It does not explicitly route the agent away from siblings such as token_risk, so it falls short of full when-not guidance.

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