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

Annotations already declare readOnly, idempotent and openWorld, so the safety profile is covered for free. The description adds genuinely non-redundant context: the per-call price ($0.04 USDC via x402), the supported chain set, and that unlimited approvals are flagged — economically important for an agent deciding to call. No return format or latency details, but the bar is lower with annotations present.

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 the capability and output contents in one dense sentence, followed by scope, use case and price. Every sentence earns its place, though the chain enumeration is somewhat redundant with the enum and could be trimmed.

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 and does so well by enumerating result fields (status, method, native/token transfers, approvals, fee, per-counterparty risk verdict, summary). It also discloses cost and chain coverage, leaving nothing essential missing for correct invocation.

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% with an enum on chain, so the schema already carries the parameter burden and baseline is 3. The description's chain list duplicates the enum rather than adding semantics, and it says nothing about the conditional `sender` requirement beyond what the schema states.

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 and resource ('Plain-language explanation of an EVM or NEAR transaction') and enumerates exactly what the explanation contains: status, method, transfers, approvals, fee, risk verdict. An agent can distinguish it from verify_allowance_receipt (a targeted allowance check) and counterparty_risk_* (address-level risk) without opening a schema.

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 sentence 'Useful to check what a payment or approval really did' implies the usage context but never states when to prefer this over the overlapping siblings verify_allowance_receipt or counterparty_risk_evm. There are no exclusions or prerequisites, so routing still requires inference.

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