Explain why a transaction failed

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

Annotations already declare readOnlyHint=true and openWorldHint=true, covering safety. The description adds behavioral context: it decodes transaction/operation result codes, provides actionable guidance, and explains the need for a protocol hint. No contradictions with 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?

Two concise sentences that front-load the core function and immediately follow with usage guidance. Every word earns its place; no redundant or vague phrasing.

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 read-only diagnostic tool with full schema coverage and no output schema, the description sufficiently conveys the return value ('plain language', 'what to do about it') and the protocol hint's role. It lacks only explicit handling of invalid hashes, but that is not essential here.

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%, with detailed descriptions for both 'hash' and 'protocol' including the rationale for the protocol hint. The description does not add new parameter semantics beyond restating the use case, 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?

The description uses a specific verb and resource: 'Look up a Stellar transaction by hash and explain its outcome in plain language.' It clearly distinguishes from sibling tools (explain_account, explain_contract) by focusing on transactions, with explicit mention of payments, swaps, and contract calls.

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 explicitly states when to use the tool: 'Use this whenever a user asks why a transaction, payment, swap, or contract call failed.' It does not explicitly name sibling tools as alternatives, but the usage context is clear and the sibling names imply when not to use this tool.

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