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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral context beyond the annotations: the identity-resolution step, the 50-substance cap, and the important semantic rule that absence from a list is reported as 'not listed'. It stops short of describing return format or partial-failure behavior.

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?

Purpose and delivery are front-loaded in the first sentence, and the exclusions close the paragraph cleanly. The middle enumeration of every inventory and list is lengthy and somewhat padded, but it directly informs list selection, so it earns most of its space.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. Combined with full scope, jurisdiction/list coverage, the 50-item limit and explicit sibling boundaries, an agent has everything needed to invoke this correctly.

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 coverage is 100%, so the baseline is 3. The description nevertheless glosses the meaning of `lists` (naming the actual regulatory mechanisms behind the enums) and `identity_only`, and confirms the accepted identifier formats (name, CAS, EC) — adding real meaning over the schema's terse per-field text.

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 states a specific verb+resource ('Checks whether one or more chemical substances... are registered, listed, restricted or banned') and scopes it further ('screens a bill of materials'). It also names the sibling tools it is NOT (GHS hazard classification, workplace exposure limits, industry-specific ingredient checks), so an agent can differentiate it without opening schemas.

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?

Explicit when-not guidance is given: 'Not intended for hazard classification, pictograms or UN numbers', exposure limits, and cosmetic/food/pesticide/biocide status, each with the sibling tool named as the alternative. The 'Accept up to 50 substances' and 'missing from a list = not listed' rules set invocation expectations clearly.

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