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

The annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful behavioral context beyond annotations: the $0.002 x402 payment model, that failed calls are not charged, the Flashbots relay source, and the newest-blocks-only limitation.

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 description is front-loaded with the dataset and returned fields, then covers scope, exclusion, and pricing in short, purposeful sentences. Each sentence contributes information needed to judge fit or cost, with no meaningful wasted text.

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?

Given the output schema, annotations, and full parameter coverage, the description supplies the missing context an agent needs: source, data fields, newest-block scope, sandwich-volume exclusion, and payment behavior. It is complete enough for correct invocation without over-explaining return values.

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?

There is only one parameter and schema description coverage is 100%; the schema already documents that 'limit' selects the newest delivered blocks, accepts 1 to 50, and defaults to 10. The description repeats the same range and scope without adding syntax, formatting, or selection details 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 the exact dataset and source—Ethereum MEV-Boost delivered blocks from the Flashbots relay—and enumerates the returned fields: block value, transaction count, gas used vs limit, and builder pubkeys. It also distinguishes the data from sandwich volume, though it lacks an explicit retrieval verb such as 'returns' or 'lists'.

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 provides scope ('newest blocks only') and a clear exclusion ('sandwich volume is not in this source'), which implies when the tool is appropriate. However, it does not explicitly state when to use this tool versus a sibling alternative, nor does it name another tool for older blocks or sandwich data.

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