Fetch a single Open Food Facts product by barcode to view its nutrition and allergen data.
Read one Open Food Facts product by barcode. Nutrition and allergen data are informational.
| Name | Required | Description | Default |
|---|---|---|---|
| barcode | Yes | ||
| language | No |
| Name | Required | Description | Default |
|---|---|---|---|
| data | Yes | ||
| source | Yes | ||
| warnings | Yes | ||
| cache_hit | Yes | ||
| retrieved_at | Yes | ||
| missing_fields | Yes |
Changes observed during successful MCP inspections.
v0.1.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds one genuinely new behavioral note — that nutrition/allergen data is informational — but says nothing about miss behavior for an unknown barcode or about the external-service nature beyond the openWorld hint.
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?
Two tight sentences with the core action and key front-loaded and no filler. Slightly thin rather than padded, but efficient.
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 described, and annotations cover safety. What remains missing is the language parameter's effect and the not-found case, which is a modest gap for a simple single-record read.
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 carries the full burden. It hints that barcode is the lookup key but gives no format constraints, and the 'language' parameter is never mentioned anywhere, leaving half the parameters semantically undocumented.
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 ('Read one Open Food Facts product') and the lookup key ('by barcode'), which cleanly separates it from search_products and compare_products. It does not explicitly name those siblings, so it stops short of a 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?
'Read one ... by barcode' implies the usage condition (you already have a barcode), but there is no explicit when-to-use/when-not statement and no routing to search_products for name or category lookups. Usage must be inferred.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.