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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: it defaults to the latest snapshot and discloses that future supply fields are Amazon source-provided In-Stock Head Start values that remain null when unavailable. It stops short of describing pagination or multi-snapshot behavior, but the null-field caveat is a meaningful disclosure.

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?

Front-loaded with the 'Use for...' purpose, followed by data-quality nuance and the routing exclusion. Every sentence carries information, though the metric enumeration in the first sentence is dense. No filler or repetition of the title.

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 an output schema present, the description need not explain return values, and it correctly focuses on scoping, defaults, null semantics, and sibling routing. For a 9-parameter, no-required-parameter tool it is nearly complete; only snapshot-history behavior is left implicit.

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 every parameter is already documented (sku, asin, limit, offset, sort_by, sort_order, snapshot_date, include_raw_rows, include_diagnostics). The description reinforces ASIN/SKU scoping and the latest-snapshot default but adds no syntax or constraint detail beyond the schema, which is precisely the baseline-3 case.

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 ('raw FBA inventory snapshot quantities per ASIN/SKU') and enumerates the exact metric families returned (fulfillable, reserved breakdowns, inbound, future supply, researching, unfulfillable). It also names the siblings it is not (get_days_of_cover, get_inventory_risk_triage), so an agent can distinguish it from the many other inventory tools without opening any 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?

Explicitly states an exclusion with the reason: 'Do not use alone for reorder or stockout priority; use get_days_of_cover or get_inventory_risk_triage.' This gives both the when-not and the named alternative, which is the strongest form of routing guidance.

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