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

Annotations already cover the safety profile (readOnlyHint=true, idempotentHint=true, destructiveHint=false), so the bar is lower. The description adds real value beyond that by disclosing what the response contains: per-jurisdiction status with its governing law, effective date, product-count, and examples. It omits any note on data freshness or jurisdiction coverage limits, keeping it out of 5 territory.

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?

One sentence, front-loaded with the action and immediately followed by the payload contents. Every clause (jurisdictions, statuses, law, effective date, product counts, examples) contributes new information with no filler or repetition.

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 no output schema, the description must carry the return-shape burden, and it does so competently by enumerating the status fields, jurisdictions, and supporting evidence. It is adequate for a simple single-parameter read tool, though it gives no indication of result size or whether unresolved additives return an empty status set.

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?

There is a single parameter with 100% schema description coverage, including concrete examples ('titanium dioxide', 'red-3'), so the schema already does the work. The description adds no extra parameter nuance such as accepted aliases, slug normalization, or partial-match behavior, so the baseline of 3 applies.

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 names a specific verb ('Returns') and a precise resource (an additive's legal status across named jurisdictions: US FDA, EU, and specific US states), with the four status categories spelled out (allowed, restricted, banned, warning). That is far more specific than the bare title. It stops short of explicitly distinguishing itself from siblings like check_product or chemical_sources, so it lands at 4 rather than 5.

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?

Usage is implied by the additive-centric framing and the sibling set (check_product covers products, not additives), so an agent can infer the right scope. However, there is no explicit when-to-use statement, no when-not-to-use, and no named alternative, which caps this at the minimum-viable level.

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