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

Annotations already declare readOnlyHint=true, and the description adds the important behavioral trait that the tool is 'Never cached' and returns 'live' pricing. This goes beyond the annotations by explaining freshness semantics, which is valuable. No contradiction exists.

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 extremely concise—two sentences that front-load the primary purpose and critical usage constraints. Every sentence adds value, with no filler or repetition of obvious schema details.

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 tool has no output schema, and the description only partially explains what the response contains (unit price and line total). It omits any detail about response structure, error handling, or the roles of the five undocumented parameters. This is adequate for a simple pricing check but leaves clear gaps.

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 only 29%, and the description only discusses variant_ids and quantity, which are already well-described in the schema. It adds no new meaning for the other five parameters (journey_id, match_type, selected_sku, result_set_id, selected_handle), failing to compensate for the low coverage.

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 clearly states the tool's purpose: to confirm live unit price and line total before cart handoff. This is a specific verb+resource combination, and it distinguishes from sibling tools like check_inventory or create_cart_url by focusing on 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 description gives clear context for when to use the tool ('before cart handoff'), which is a strong usage signal. It also provides a critical constraint ('Never send variant_ids as numbers'), but it does not explicitly enumerate when not to use it or name alternative tools, so it misses the top tier.

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