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

The description depicts a pure lookup ('check what a transaction did or whether it exists'), i.e. a read operation, while the annotations declare readOnlyHint=false and idempotentHint=false. That is a direct conflict about the tool's side-effect profile. The cost disclosure ("$0.001 in USDC on Base per successful call, paid with x402") is genuinely useful added context, but it does not resolve the read/write contradiction.

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?

Three sentences, front-loaded with the resource and its returned fields, then usage, then cost. Every sentence carries information 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?

With no output schema, the description usefully enumerates the returned fields, and it discloses the payment model an agent must know before calling. It omits behavior for a missing/invalid hash or error conditions, which keeps it short of complete.

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?

Only one parameter (hash) with 100% schema description coverage, so the schema already carries the meaning. The description adds nothing about the hash format, and per the high-coverage baseline a 3 is appropriate.

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 states the resource precisely (an Optimism transaction, looked up by hash) and enumerates the exact returned fields (sender, recipient, value, nonce, gas limit, selector, block), which implicitly separates it from siblings like op_receipt or op_logs. It lacks an explicit action verb, opening instead with a noun phrase, but the scope is unambiguous.

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?

'Use to check what a transaction did or whether it exists' gives a clear usage context, but no when-not guidance and no named alternative among the many op_* siblings (op_receipt, op_logs, op_block). Usage is implied rather than routed.

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