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

With no annotations provided, the description carries the full behavioral disclosure burden. It adds important access behavior: the API key bearer token requirement and the per-call payment option, plus a cost of 2 cents per call. It also states window limits (default 24, max 720), which affects agent expectations. It does not mention rate limits or explicitly state read-only behavior, but the main cost/access/window behaviors are disclosed, and the output schema covers return shape.

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 entire description is a single block that front-loads lengthy payment details before the core purpose. The payment alternative details are actionable but verbose, and the actual market-data purpose appears later in the sentence. Still, every piece of information is relevant to calling the tool successfully, and there is no filler.

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?

For a simple tool with one optional parameter, the structure defines the data returned, the window bounds, and the required authorization/payment path. The output schema exists to clarify return fields. Missing contextual elements—such as integration with other MEV-related siblings or handling of invalid windows—are relatively minor for making a correct call.

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 input schema only declares a number property with no description, so schema coverage is 0%. The description compensates well by explaining that window is in hours, with a default of 24 and an upper bound of 720. It could add what larger windows mean for result granularity, but for a single optional parameter the description fills the main gaps.

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 clearly names the resource—the Ethereum block builder market—and the metrics returned: blocks delivered, value per relay, and top builders by value. It does not use an explicit verb like 'returns' or 'lists', but the meaning is unambiguous. It does not explicitly differentiate from sibling tools, though none of the siblings appear to cover the same builder-relay scope.

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 description implies that the tool is used to query block builder market data over a user-specified window, and it gives default and maximum window bounds. However, it provides no explicit guidance about when to choose this tool over alternatives, no exclusions, and no mention of related MEV tools that might overlap.

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