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

With no annotations, the description carries the full burden, and it does disclose two important behaviors: it is a paid endpoint ($0.005 USDC on Base) using the x402 protocol. However, it says nothing about rate limits, caching/freshness of 'live' data, or what happens when payment is absent — the latter only appears in the schema parameter text.

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?

Two short sentences, front-loaded with what the tool returns and backed by cost/payment info; no filler. Slightly telegraphic, but every clause carries information an agent needs before paying for a call.

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?

There is no output schema, so the description must convey return shape, and it partly does (per-chain gas, USD transfer/swap cost, cheapest chain). It omits which 7 chains, the response structure, and the two-step pay-first flow, which for a paid endpoint is a meaningful gap.

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% and there is only one optional parameter, so the schema already fully documents the x402_payment payload and the omit-to-receive-terms flow. The description adds only the price and chain, matching the baseline of 3 for a single well-documented parameter.

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 names the resource precisely (live gas on 7 EVM chains) and the specific outputs (USD cost of transfer/swap, cheapest chain), which tells an agent exactly what it gets back. It distinguishes itself from siblings like pricing and token_risk by being gas-focused, though it never uses a verb like 'fetch' or 'return'.

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?

There is no explicit when-to-use statement, no exclusions, and no named alternative among siblings (e.g. pricing) that might also return cost data. The only usage-adjacent signal is the payment note, which is about mechanics rather than about choosing this tool.

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