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

Adds substantial context beyond readOnlyHint/openWorldHint: data source is public RPC, the hard 5,000-block window, what decoding is applied, what is excluded, and — critically for a paid endpoint — that each successful call costs $0.002 USDC via x402 while failures are free. An agent can budget and predict behavior from this.

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 dense sentences with the resource and scope front-loaded, followed by limits, exclusions, and pricing. Nothing is repeated from the annotations and every clause carries 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?

Output schema exists so return shape needn't be spelled out, annotations cover safety, and the description supplies the remaining gaps: cost model, chain ID, data provenance, lookback ceiling, and decoding behavior. Nothing an agent needs to invoke it correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description goes further by explaining that the event name comes from a signature database, the topic filter is a signature hash, and the block window maps to roughly 2.8 hours of history. That adds real interpretation value over the bare schema descriptions.

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 — recent event logs for a contract on Base (chain 8453) — plus the exact payload returned (block, time order, tx hash, log index, event name, topics/data, decoded ERC-20/721 Transfer/Approval). An agent knows precisely which resource and which chain this targets, and no sibling in the list covers Basescan contract logs.

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?

Gives concrete operating boundaries: look back at most 5,000 blocks (~2.8 h), optional event-signature filter, and an explicit exclusion ('Internal transactions are not included'). It doesn't name an alternative tool or say when a different scanner would be preferred, so it falls just short of a 5.

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