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

With no annotations, the description carries the full burden and does so: price and payment protocol ($0.004 USDC/call via x402, eip155:8453), supported signature schemes (EOA EIP-712 only; ERC-1271/6492 unsupported), 64 KiB body cap, and the important caveat that input facts are unauthenticated. Normalization limits (NFKC/case/whitespace only, no synonym or chemical equivalence) are disclosed so the agent knows what the diff does not detect.

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 core purpose in the first clause, then scope limits, then payment constraints. Nearly every sentence earns its place, though the payment/protocol boilerplate is dense and slightly crowds out the input-contract details that are undocumented elsewhere.

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?

For a nested 3-parameter tool with no annotations and no output schema, the description covers the operation, the result categories, the size and normalization limits, and the payment path. Missing pieces are the exact response structure and what happens when top-level product_id disagrees with the product_id inside before/after.

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 0%, so the description must compensate and it only partly does: it confirms the 1000-ingredient-per-list cap and the name-normalization rules, which map to the ingredients array and name field. It says nothing about the declared_at string format (max 64 chars), the percentage string pattern, or the ambiguous duplication of product_id at top level and inside both before/after objects.

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 pair ("Compare two supplied dated ingredient lists for the same declared product") and enumerates the diff outputs (added/removed normalized names, order, percentage changes). This is clearly distinct from adjacent siblings like product_content_impact, fragrance_check, or migration_compare.

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 opening clause establishes the precondition (two dated lists for the same declared product) and the description explicitly fences off out-of-scope uses: "No synonym, chemical equivalence, toxicology, allergy, medical or regulatory conclusion." It does not name a sibling alternative for those excluded cases, so it stops short of explicit routing.

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