get_transaction

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

No annotations are provided, so the description carries the full burden. It discloses the return payload (full transaction object with specific fields) and the error behavior (NOT_FOUND if ID doesn't exist). While it doesn't explicitly state it's read-only, 'look up' implies no side effects. This is adequate for a simple get-like tool.

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 sentences with no fluff. The first sentence states the action and key detail (single, by ID). The second sentence adds valuable return-content and error information. Every word earns its place.

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 one-parameter lookup tool with no output schema and no annotations, the description is complete: it explains the action, the required input, the return contents, and the error condition. There is no missing critical information for an agent to decide to invoke 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 input schema already provides 100% coverage: the only parameter 'id' has a description with format (TXN-XXXXXXXXX) and is required. The description adds no extra meaning about the parameter beyond 'by its ID', which is redundant. Baseline 3 applies because schema coverage is high and the description doesn't need to compensate.

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 starts with a clear verb and resource: 'Look up a single FinPay transaction by its ID.' The word 'single' and 'by its ID' distinguishes it from the sibling tool list_transactions, which presumably returns multiple transactions. It also specifies the return content (status, amount, currencies, etc.), making the purpose 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?

The description clearly implies the tool is for fetching a specific transaction when you already have its ID. It does not explicitly name alternatives like list_transactions for cases without an ID, but the phrasing 'by its ID' provides context and implies a precondition. No exclusions are stated, but it's enough for clear context.

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