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

Annotations alone would leave readOnlyHint=false puzzling for a read-style tool; the description explains it ('Reads or computes only; not marked read-only because each call is charged'), which resolves the apparent anomaly. It also discloses pricing ($0.003/call, 25 free, failed calls free) and the result cap (up to 100 logs with block, tx hash, topics), going well beyond the annotations.

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?

Core purpose and block range are front-loaded, then filtering, return shape, alternative, and pricing in a logical order. The pricing/annotation sentence is dense but each clause (price, free tier, failed-call policy, read-only rationale) carries real 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?

Despite no output schema, the description covers return cardinality and fields, the filter option, the when-to-use alternative, and the full cost model plus the annotation rationale. Nothing an agent needs to call this 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 blocks (1-1000, default 50) and topic0 are already documented. The description restates them and adds only a small semantic gloss on topic0 as the '32-byte event signature hash', so the baseline 3 applies.

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 (List), resource (recent event logs), and scope (a contract on Optimism over the last N blocks), then explicitly names the sibling it is not (op_receipt). An agent can distinguish it from the ~60 sibling log/receipt tools immediately.

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 a concrete use case ('watch transfers or contract events') and an explicit exclusion with the alternative ('for one transaction's outcome use op_receipt'). Nothing is left to inference about when to pick this over a receipt call.

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