Red Good Wine

Red Good Wine Price Index

price_index

Read-onlyIdempotent

The Red Good Wine Price Index: how many shops and bottles are tracked, the median saving from shopping around, and today's biggest price gaps between shops for the same bottle.

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "price_index"
  }
}

Input Schema

Name	Required	Description	Default
No arguments

Output Schema

Name	Required	Description	Default
`url`	Yes
`top_deals`	Yes
`comparisons`	No
`generated_at`	No
`shops_tracked`	Yes
`products_tracked`	No
`median_savings_pct`	No

Schema Changelog

Changes observed during successful MCP inspections.

First observedNov 13, 2026

TDQS

A3.6/5.0

Behavior3/5

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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered and the description correctly does not contradict it. The description adds useful scope information about which aggregate metrics are returned (median saving, biggest price gaps). It does not mention data freshness or the time window beyond 'today', which would be valuable for a price index.

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

Conciseness4/5

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

A single sentence with a colon-delimited list of the three metric families, front-loading the tool's identity before the contents. No filler or redundant restatement of the title beyond the leading identification.

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

Completeness4/5

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

This is a zero-parameter, read-only aggregate tool with an output schema, so the description only needs to convey what the snapshot contains, which it does. The remaining gap is data recency/coverage (e.g., how 'today' is defined), which matters for a price index over time.

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

Parameters4/5

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

The tool takes no parameters, so there is nothing for the description to disambiguate and the baseline is 4. Schema coverage is reported at 100% with an empty properties object, so no gaps exist to compensate for.

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?

The description names a specific resource (Red Good Wine Price Index) and enumerates its scope: shops and bottles tracked, median saving from shopping around, and today's biggest price gaps. That is enough to distinguish it from siblings like best_price or bottle_offers, which deal with individual bottles rather than an aggregate market snapshot. It is slightly noun-phrase descriptive rather than verb-led, but the resource is unambiguous.

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?

The listed contents imply this is an overview/statistics tool to call for a market-level summary rather than a per-bottle lookup, but the description never states when to use it versus best_price, bottle_offers, or search_bottles. There are no explicit exclusions or routing cues, leaving the agent to infer the alternative from the content list.

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

All Red Good Wine tools Inspect

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