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

Annotations already declare readOnlyHint=true, openWorldHint=true, and destructiveHint=false. The description adds useful context: it is live SP-API data, returns eligibility status and Amazon ineligibility reason codes, and belongs to a specific signal family. Auth and rate-limit behavior are not disclosed, but the annotation coverage lowers the bar.

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, front-loaded with the core purpose and then the usage context. Every sentence earns its place with 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?

With a full schema, output schema, and informative annotations, the description completes the picture by stating live behavior, return content, and sibling pairing. Nothing an agent needs to invoke this correctly is missing.

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% and all four parameters are documented in the schema, so the description adds no parameter semantics beyond it. It mentions the ASIN concept but nothing about the program enum or include_raw_rows/include_diagnostics toggles. Baseline 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?

States a specific verb (check eligibility), resource (ASIN for FBA), and scope (live SP-API), and explicitly distinguishes itself as one of the buyability signals alongside named siblings. An agent can pick this tool 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?

Explicitly tells the agent to pair this with get_buybox_status, get_listing_restrictions, and get_suppressed_listings for a full buyability check, effectively naming alternatives and the condition that selects each. This is precise routing guidance.

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