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

Annotations already declare readOnly/idempotent/closed-world, so the safety profile is covered. The description adds genuinely non-obvious behavior: it returns detected chains with a confidence note, a checksummed EVM form, and the exact failure reason, plus a payment/auth requirement ('$0.05 per successful call, paid over x402 (USDC on Base)') that the annotations do not convey.

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 purpose, then outputs, then pricing — a sensible ordering. The long chain enumeration is information-dense and earns its space, though it slightly crowds the sentence structure.

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 correctly compensates by describing return values (detected chains, confidence, checksummed form, failure reason) and adds pricing/auth context. It never explains the meaning of the 'confidence note' or error shapes in detail, leaving a small gap for a 3-param tool with a paid, openWorld-flagged operation.

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%, so the baseline is 3. The `chain_id` EIP-1191 behavior and the `expect` enum are already fully documented in the schema; the description's encoding list is about capability, not parameter meaning, so it adds little beyond the structured fields.

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 pair ('Identify which blockchain an address belongs to and validate its encoding') and enumerates the exact chains and encodings covered (EIP-55, base58check, bech32/bech32m, SS58). An agent can immediately tell this is an address-format/checksum tool rather than a hash, geo, or id tool from the sibling set.

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 is implied by the purpose (feed it an address to detect/validate), but there is no explicit 'when to use this vs chain_selector' statement or any exclusion. The 'expect' restriction is only surfaced in the schema, not the description, so alternatives/conditions are left to inference.

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