iwantmymtg-mcp

add_buy_list

Add a card to your MTG buy list, increasing the quantity and creating an entry if absent.

Instructions

Add a card to the authenticated user's buy-list, incrementing the quantity (creates the row if absent). This is a real write. Use update_buy_list to set an absolute quantity or remove_buy_list to delete a row. Requires IWMM_API_KEY.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "cardId": "<cardId>"
    },
    "name": "add_buy_list"
  }
}

Input Schema

Name	Required	Description
`cardId`	Yes	Internal IWMM card UUID. Get from search_cards or get_card.
`isFoil`	No	Whether this is the foil variant. Foil and non-foil are separate rows. Defaults to false.
`quantity`	No	How many to add. Defaults to 1.

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.6.2Jul 9, 2026
- addedInput schema / $schema
```
Added value: +"http://json-schema.org/draft-07/schema#"
```
Addedv0.5.0Jun 17, 2026

TDQS

A4.5/5.0

Behavior4/5

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

With no annotations, the description carries the full burden and adequately discloses that the tool performs a real write, increments quantity, and creates a row if absent. It does not mention potential errors or rate limits, but overall transparency is high.

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?

The description is two sentences: the first covers core behavior, the second gives usage alternatives and auth requirement. No extraneous information; every sentence adds value.

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

Completeness5/5

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

For a simple add tool with three well-documented parameters and no output schema, the description fully covers usage context, alternatives, and authentication needs. It is complete and self-contained.

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?

Input schema has 100% description coverage with well-described parameters (cardId UUID, isFoil boolean, quantity integer). The description adds no additional parameter-specific details beyond the schema, so baseline 3 is appropriate.

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

Purpose5/5

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

The description clearly states the action (add a card) and resource (buy-list), and explicitly distinguishes it from update_buy_list and remove_buy_list, which are sibling tools with different semantics.

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

Usage Guidelines5/5

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

The tool description explicitly provides when-to-use guidance by naming alternatives (update_buy_list for absolute quantity, remove_buy_list for deletion) and mentions the authentication requirement (IWMM_API_KEY).

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

Deploy Server