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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds substantial context beyond annotations: the output shape, an example response, the price and payment mechanism, and the fact that it returns both a summary and structured facts. This is strong behavioral disclosure for an AI-powered, paid, read-only lookup.

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 front-loaded with the core purpose and then adds return format and pricing details. The example output is somewhat lengthy, but it earns its place by illustrating the summary-plus-facts return shape that is not captured in an output schema.

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 carries the burden of explaining returns; it does so with a clear example and a statement that it returns a summary plus structured facts. Combined with the pricing and payment requirement, an agent has enough context to invoke the tool correctly.

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 description coverage is 100%, so both parameters are already documented in the schema. The description reinforces the supported chain values and implies the hash identifies the transaction, but it does not add much syntax or format detail beyond what the schema provides. 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?

States a specific verb and resource: 'Explain a transaction in plain English (AI)' and specifies the supported chains. It is clearly distinguished from siblings like base_tx_status or token_transfers because it produces a natural-language summary rather than raw status or transfer lists.

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 makes the tool's purpose and supported chains clear, and it explains that payment is required via x402 in _meta. However, it does not explicitly say when to choose this over base_tx_status, token_transfers, or evm_block, nor does it state exclusions such as unsupported chains or failed lookups.

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