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

Annotations already cover the read-only/idempotent/non-destructive safety profile, and the description adds substantially more: public RPCs, no charge on bad input or RPC downtime, x402 payment pricing in USDC on Base (MCP payments Base only), and an explicit warning that returned content is untrusted third-party data. That is rich behavioral context beyond the 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?

Dense but front-loaded: purpose first, then inputs, then return shape, then cost and safety caveats. Every sentence carries information, though it is on the long side and could be split for scannability.

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?

No output schema exists, and the description compensates by enumerating the return fields (status, final, confirmations, block, fee, decoded token transfers, pollAgainSeconds), plus coverage of cost and input validity. Nothing an agent needs to call it correctly is missing.

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 schema already documents both params, and the description largely repeats the accepted network values and the 0x-hash requirement. It adds only marginal value (the poll-until-final hint) beyond what the schema states, 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?

The description states a specific verb and resource: it answers 'did a payment or swap land, and is it final.' It also names the two required inputs, so an agent can distinguish this status-lookup from siblings like tx_guard without opening the 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?

Usage is well-pictured: GET semantics, required tx, and network only for 0x hashes, plus an explicit retry rule ('poll again after pollAgainSeconds until final is true'). It does not explicitly name when to prefer this over tx_guard, but the operational context is clear.

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