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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false. The description adds useful behavioral context beyond that: absence of withdrawal does not mean approval, shared names return an options object, and SANTE records include all CAS entries after arbitration of shared CAS numbers.

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 main paragraph is front-loaded and informative, but the source/provenance paragraph includes unrelated platform datasets such as Parcelles RPG and SISE-Eaux tap water, which add clutter for a substance lookup. The tool-specific information is dense and useful, but the description could be trimmed.

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 does a good job listing the substantive fields and caveats an agent should expect. It does not specify what happens if neither cas nor name is supplied, and the exact return shape for normal versus shared-name cases is only partially described.

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 100%, so the two parameters are already documented. The description still adds meaning by naming the accepted name sources (EFSA name, BNVD French label, water-control label, SANTE name) and by explaining the shared-name options behavior.

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 identifies a substance/metabolite lookup and enumerates the specific content returned: toxicity, endocrine-disruptor status, EU withdrawal/non-renewal, SANTE records, and parent molecules. This is far more specific than a restatement of the title and makes the resource distinguishable from the commune/water-focused siblings.

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?

It gives concrete identifier guidance: CAS number is the safest identifier, with name as fallback, and it explains that shared names such as “cuivre” return an options field. It does not explicitly state when not to use the tool or name alternatives, but no sibling tool covers the same substance-lookup purpose.

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