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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the 'READ-ONLY' prefix is redundant. The description adds valuable behavioral context: it uses async SP-API reports and the first call may take 30-60 seconds, and it cross-references existing reimbursements to avoid double claiming. It does not contradict 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 front-loaded with the tool's core action and scope, followed by usage examples and two practical notes (Seller Central case handling, async delay). It packs relevant information efficiently, though the Italian-language example phrases add some length that could be trimmed for non-Italian agents. Overall it earns its space with useful routing and behavioral cues.

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?

With no output schema, the description adequately explains what the tool returns: per-shipment units received, Amazon-flagged unreconciled quantities, estimated recoverable value, and cross-referenced reimbursements. It also covers latency and the fact that opening a case is out of scope. All information needed to invoke and interpret the tool is present.

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 the schema fully documents both parameters (days and account_id). The description adds no parameter-specific details beyond what the schema provides, which is the baseline expectation when coverage is high. A score of 3 is appropriate because the schema does the heavy lifting.

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 states a specific verb and resource: reads the inventory ledger (Receipts) to show FBA shipment discrepancies and recoverable value. It clearly distinguishes itself from sibling tools by explaining that it cross-references already-granted reimbursements and that opening a reconciliation case is not available via API. An agent can identify the tool's exact function without opening the schema.

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?

It gives explicit use cases including Italian-language queries ('controlla le spedizioni FBA / unità mancanti / cosa recuperare / rimborsi FBA'), which helps routing. However, it does not name alternative sibling tools like get_fba_inventory or get_fba_customer_returns, so an agent still has to infer the best tool among related FBA report options. The note about Seller Central clarifies an out-of-band process but not a tool alternative.

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