Bikefuchs — Bike Parts Price Comparison

Find Alternative Shops

find_alternatives_for_product

Read-onlyIdempotent

Given a product's EAN barcode, return every shop that carries it with prices and availability, sorted cheapest-first.

Input Schema

Name	Required	Description	Default
`ean`	Yes	EAN barcode (8–14 digits, e.g. '4524667749493')
`country`	No	Country for pricing (DE or AT, default DE)	DE

Output Schema

Name	Required	Description	Default
`ean`	Yes
`disclosure`	No
`shop_states`	No
`alternatives`	Yes
`product_name`	Yes
`pending_shops`	No
`not_found_shops`	No
`refresh_pending`	No
`refresh_required`	No
`retry_after_seconds`	No
`cheapest_price_stale`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedNov 5, 2026

addedOutput schema / properties / not_found_shops

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / pending_shops

Added value: +{
+  "items": {
+    "type": "string"
+  },
+  "type": "array"
+}

addedOutput schema / properties / refresh_required

Added value: +{
+  "additionalProperties": false,
+  "properties": {
+    "instruction": {
+      "type": "string"
+    },
+    "retry_after_seconds": {
+      "type": "number"
+    }
+  },
+  "required": [
+    "retry_after_seconds",
+    "instruction"
+  ],
+  "type": "object"
+}

addedOutput schema / properties / shop_states

Added value: +{
+  "items": {
+    "additionalProperties": false,
+    "properties": {
+      "affiliate_url": {
+        "type": "string"
+      },
+      "price": {
+        "anyOf": [
+          {
+            "type": "number"
+          },
+          {
+            "type": "null"
+          }
+        ]
+      },
+      "shop": {
+        "type": "string"
+      },
+      "shop_id": {
+        "type": "string"
+      },
+      "state": {
+        "type": "string"
+      }
+    },
+    "required": [
+      "shop",
+      "shop_id",
+      "state",
+      "price"
+    ],
+    "type": "object"
+  },
+  "type": "array"
+}

Changed5 schema fields changedOct 20, 2026
- addedOutput schema / properties / alternatives / items / properties / price_as_of
```
Added value: +{
+  "type": "string"
+}
```
- addedOutput schema / properties / alternatives / items / properties / price_stale
```
Added value: +{
+  "type": "boolean"
+}
```
- addedOutput schema / properties / cheapest_price_stale
```
Added value: +{
+  "type": "boolean"
+}
```
- addedOutput schema / properties / refresh_pending
```
Added value: +{
+  "type": "boolean"
+}
```
- addedOutput schema / properties / retry_after_seconds
```
Added value: +{
+  "type": "number"
+}
```
Changed1 schema field changedSep 19, 2026
- addedOutput schema / properties / disclosure
```
Added value: +{
+  "type": "string"
+}
```
First observedJun 22, 2026

TDQS

A3.5/5.0

Behavior3/5

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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the safety bar is low. The description adds useful context: results are exhaustive ('every shop that carries it'), include prices and availability, and are ordered cheapest-first. It does not mention what happens with zero matches or how the country parameter affects availability versus pricing.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

One front-loaded sentence with no filler. The input, output contents, and sort order are all delivered compactly.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists and annotations are rich, so the description needn't explain return values or safety. However, given six siblings with overlapping product/price purposes, the definition leaves the agent without routing guidance and never mentions the country parameter's effect on results.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so both ean and country are fully documented in the schema with pattern and enum constraints. The description only echoes the EAN input and says nothing about the country parameter or its default, so it adds little beyond structured data. Baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('return every shop that carries it with prices and availability') and clarifies the ambiguous tool name 'find_alternatives' as meaning alternative shops rather than alternative products. It does not explicitly distinguish itself from sibling get_best_price, which covers similar ground.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: 'every shop ... sorted cheapest-first' hints at a full-listing use case versus get_best_price's single-result case, but no when-to-use or when-not-to-use statement is given. The agent must infer the choice between this tool, get_best_price, and search_product from the phrasing alone.

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

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