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 a genuinely important trait: the tool is paid ($0.001 via x402 in USDC on Base). That cost/payment disclosure is exactly the kind of context annotations would normally supply. It does not cover auth requirements, rate limits, or failure behavior, so it is not a full 5.

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?

A single sentence with the payment terms front-loaded, followed by the returned fields and the intended use. Every clause earns its place and nothing is padded.

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 and no annotations, so the description must explain the return values, which it does adequately (gas price, base fee, priority fee, units). Combined with the cost disclosure, an agent has enough to call it correctly; only freshness/latency and error behavior are left unstated.

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?

The tool takes zero parameters, which is the baseline-4 case: there is nothing for the description to clarify beyond what the empty schema already shows. No param-level meaning is missing.

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 (live Base gas) and enumerates exactly what it returns: gas price, EIP-1559 base fee, and suggested priority fee in Gwei. This cleanly separates it from siblings like get_latest_block or get_crypto_price without needing to open any 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 phrase 'Tx cost planning for agents' gives a clear use context, and no sibling tool overlaps with gas-fee retrieval, so no alternative needs to be named. It stops short of explicit when-not-to-use conditions, which keeps it out of 5 territory.

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