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

Annotations already declare readOnlyHint and openWorldHint, and the description does not contradict them. It adds genuinely non-schema context: the output is rule-based with no AI, the cost ($0.005, x402 paid), and the six supported chains. This is useful behavioral disclosure beyond the structured fields, though it omits latency or failure-handling behavior.

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 core purpose, then dense enumerated detail that all earns its place given the richness of the return. Slightly sprawling as a single run-on sentence, but no filler.

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 burden of explaining return values and does so exhaustively (action classification, USD net changes, approve events, decoded calls, fees). Safety is covered by annotations and payment/coverage are disclosed, leaving nothing an agent needs to invoke it correctly.

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?

Both parameters are fully documented in the schema (100% coverage), so the baseline is 3. The description restates the supported chains, which loosely maps to the chain enum but adds only display-name context ('BNB Chain' vs 'bsc') beyond what the schema already provides.

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 (explain) and resource (mined transaction) and enumerates exactly what the explanation covers: swap/transfer/approval/NFT actions, net token deltas, movements, approvals, decoded function, and fee. The 'mined' qualifier implicitly separates it from the sibling simulate_tx, which acts on unexecuted transactions.

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 'any mined transaction' but there is no explicit when-to-use, when-not, or named alternative (e.g., simulate_tx for previewing, token_flows for raw movement data). An agent must infer the boundary from the phrase 'mined'.

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