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

Annotations already declare readOnlyHint and openWorldHint, so the bar is lower. The description adds meaningful behavior: payment amount and payTo address, unknown-hash handling (found:false), response key list, and an explicit exclusion of mempool tips. The phrasing 'paid 200' is ambiguous but does not contradict 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?

The description is short and packs many facts, which is good, but it is fragmented and front-loads payment details before the core action. Phrases like 'paid 200' and 'inputLen only' are jarring and would be clearer with minimal restructuring. It is concise but not well structured.

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?

There is no output schema, so the description compensates by listing expected fields and unknown-hash behavior, which is helpful. However, key details are underspecified: what 'paid 200' means, how the payment is collected, and what 'inputLen only' implies for the result. For a one-parameter tool this is adequate but not 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?

Schema coverage is 100%: the schema already documents hash as a 0x-prefixed 32-byte Base transaction hash. The description adds little parameter-level meaning beyond restating '0x hash' and mentioning 'inputLen only', which is not clearly tied to the hash parameter. Baseline 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 identifies a specific operation: transaction + receipt lookup for a 0x hash on Base, and lists the returned fields. This is distinguishable from siblings like block or token. However, the opening 'Paid $0.01 USDC exact' frames the tool in an unusual way and no sibling is named, so it is not perfectly crisp.

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?

There is no explicit guidance on when to use this tool versus alternatives. 'Not a mempool tip' is a negative filter but does not direct the agent to another tool, and 'inputLen only' is cryptic. The agent is left to infer selection criteria from the tool name alone.

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