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

With no annotations, the description carries the full burden and does disclose the important non-obvious traits: a per-call price ($0.005) settled over x402 in USDC, and a self-describing result field (timingMatters) that signals when the answer is meaningless for a chain. It does not cover rate limits, failure modes, or latency, which keeps it short of a 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?

The trigger condition is front-loaded in the first clause, followed by outputs, exclusions, and pricing in a tight sequence with no filler. The main sentence is dense and long, which costs some readability but every clause adds information.

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 the description compensates by enumerating the result components (current cost, percentiles, current position, timingMatters), which is exactly what an agent needs to interpret the response. Payment mechanics are also covered; only error and edge-case behavior is 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?

Schema description coverage is 100%, so both `chain` and `blocks` are fully documented in the schema, making 3 the baseline. The description adds only a loose hint that the window is '~1000 blocks', which aligns with the blocks default of 1024 but gives no syntax or formatting detail beyond the schema.

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 a specific resource (fee paid across the last ~1000 blocks of a chain) and specific returns (cost now, window percentiles, position of now, timingMatters) in one call. It is clearly distinguishable from evm_gas, evm_estimate_gas and evm_fees, which it also names explicitly.

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?

It states the decision context directly ('Use when an agent can choose WHEN to send and must decide whether waiting would save anything') and gives two explicit exclusions with the alternative endpoints for each (/v1/evm/estimate-gas and /v1/evm/fees). Both when-to-use and when-not-to-use are covered.

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