Compare nutrition data for 2–5 products by barcode when their normalized basis and preparation match, enabling valid side-by-side comparisons.
Compare 2–5 products only when normalized nutrition basis and preparation match.
| Name | Required | Description | Default |
|---|---|---|---|
| barcodes | 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 readOnly, idempotent, non-destructive and open-world, so the safety profile is covered. The description adds a useful domain constraint about comparability (basis/preparation must match), but says nothing about failure behavior when products are incomparable, rate limits, or scope.
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?
A single front-loaded sentence with the verb and cardinality first and the conditional constraint second — no filler. It is arguably too terse for a two-parameter tool with no schema documentation, which keeps it from a 5.
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 the comparability precondition is stated. But with 0% parameter coverage and two undocumented params, an agent still lacks enough to invoke confidently — the language parameter and barcode input format are unexplained.
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, yet it only echoes the 2–5 count constraint already encoded in minItems/maxItems. It never states that the input is barcodes (the required array) or what the optional language parameter controls.
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 and resource ("Compare 2–5 products") and scopes the operation with a validity condition. It does not differentiate itself from siblings like get_product or search_products, so an agent must infer when comparison beats a simple lookup.
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 supplies a real precondition — only compare when normalized nutrition basis and preparation match — which is genuine usage guidance. However, it never names an alternative or says when not to use this tool versus search_products or get_product, leaving the sibling choice to inference.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.