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

Discloses that the tool forwards to the owning seller (network call) and that it returns price, stock, and purchase requirements. No annotations existed, so description fully covers behavioral traits.

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 critical information front-loaded. First sentence states core purpose, second gives parameter guidance and return info, third explains forwarding and buy loop. No wasted words.

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?

Despite no output schema, the description fully explains the tool's role in a multi-step buy flow, parameter provenance, and what the response contains. Complete for a single-listing detail fetch tool.

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%, but the description adds value by specifying the exact source of the parameter values (mcp_ref.seller_mcp_url and mcp_ref.product_id from discovery results), which is not in the schema.

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 specific verb 'Fetch' and resource 'full detail for ONE listing', clearly distinguishing it from sibling tools like find_seller or get_seller_products by focusing on purchase intent. It also positions itself within a buying workflow.

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 when to use ('before buying'), how to pass parameters ('exactly as they appear in find_seller / get_seller_products result'), and places the tool in a sequence (get_product -> get_shipping_quote -> buy_product). Provides both usage context and alternative steps.

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