explain_tx

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It explicitly states 'Informational only — never authorization,' which is a strong guarantee that this tool does not perform any mutating or authorization actions. It also indicates the output is human-readable summary lines, giving the agent a clear expectation of the response type. While it does not mention error behavior or edge cases, the key behavioral trait (read-only, non-authorizing) is clearly disclosed.

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 two sentences with no wasted words. The primary action and output are stated in the first sentence, and the critical caveat (informational only) is placed in the second. It is front-loaded with the essential purpose and includes only necessary details. Perfectly concise.

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?

For a tool with one parameter, no annotations, and no output schema, the description is sufficiently complete. It explains what the tool does, what the output looks like (human-readable summary lines with specific components), and its informational nature. It does not detail error handling or missing-transaction behavior, but for a read-only decoder this is acceptable. The description covers all essential aspects an agent needs to call it 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?

The schema provides a 100% description coverage for the single parameter 'hash,' specifying it as a lowercase hex 0x-less 64-character string. The tool description only references 'by hash' without adding additional meaning beyond what the schema already provides. Since the schema fully documents the parameter, the description does not need to add more, so a baseline of 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 clearly states the action: 'Fetch a transaction by hash and decode it into human-readable summary lines.' It specifies the resource (transaction by hash) and the output format (summary lines with messages, amounts, fees, tax). This clearly differentiates it from siblings like simulate_tx (which simulates) and balance (which checks balances). The purpose is unambiguous and specific.

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 provides clear context: use this when you have a transaction hash and want a decoded human-readable summary. The phrase 'Informational only — never authorization' implies it is for reading, not for executing or authorizing, but it does not explicitly name alternatives or exclusions. There is no explicit when-not-to-use guidance, but the context is sufficient for an agent to infer its appropriate use.

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