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

The description adds 'Never cached' which aligns with and extends the annotations (readOnlyHint, openWorldHint). It also warns 'Never send variant_ids as numbers,' a behavioral constraint beyond the schema. These additions provide useful operational context.

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 a tight three sentences, front-loaded with the primary purpose. Every sentence adds value: usage context, required argument, and a warning about caching and ID types. No filler or redundancy.

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?

The description covers the main use case and critical ID format warning well. However, with no output schema and five undocumented parameters, there is a meaningful gap in understanding what the tool returns and how optional parameters affect behavior. For a tool with this complexity, more detail is needed for full completeness.

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 description repeats schema information for variant_ids and quantity, but adds the critical warning about string vs. number. However, it does not explain the five other parameters (journey_id, match_type, selected_sku, etc.) which have no schema descriptions. Given the low schema coverage (29%), the description should compensate more but doesn't.

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?

Description clearly states the tool's purpose: 'confirm live unit price and line total before cart handoff.' The verb 'confirm' and resource 'live unit price and line total' are specific. It also distinguishes from sibling tools like get_shipping_estimate or create_cart_url by scoping it to pre-handoff pricing confirmation.

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 phrase 'before cart handoff' provides clear context for when to use this tool. However, it does not explicitly mention alternatives or when not to use it. Given the sibling list includes related pricing/quote tools, an explicit exclusion would strengthen this, but the implied usage is clear enough.

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