Mercari MCP Server

create_listing

Create a new product listing on Mercari by providing title, description, price, condition, and optional images, category, and shipping location.

Instructions

Create a new listing on Mercari

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": {
      "title": "<title>",
      "description": "<description>",
      "price": "<price>",
      "condition": "<condition>"
    },
    "name": "create_listing"
  }
}

Input Schema

Name	Required	Description
`price`	Yes	Listing price in USD
`title`	Yes	Item title
`images`	No	Local file paths or URLs of item images
`category`	No	Item category
`condition`	Yes	Item condition
`description`	Yes	Item description
`shipping_from`	No	Ship from state code (e.g. 'CA')

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Jul 28, 2026

TDQS

B3.1/5.0

Behavior2/5

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

No annotations are present, so the description carries full burden. It only says 'Create', implying a write operation, but gives no details about side effects, authorization needs, or success/error behavior. More context is needed.

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?

The description is a single sentence, concise and front-loaded. However, it is so brief that it feels under-specified rather than efficiently written. Slightly more detail would improve it without losing conciseness.

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

Completeness2/5

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

Given the tool has 7 parameters, 4 required, and an enum for condition, the description is too sparse. It does not explain what happens upon creation (e.g., returns listing ID), any constraints, or required setup. Lacks completeness.

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 description coverage is 100%, so the schema already documents all 7 parameters. The description adds no extra information about parameters, hence baseline score of 3 applies.

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 'Create a new listing on Mercari', with a specific verb and resource. It distinguishes well from sibling tools like get_my_listings or search_listings which are read operations.

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

Usage Guidelines2/5

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

The description provides no guidance on when to use this tool versus alternatives, nor does it mention any prerequisites or restrictions. It lacks explicit when-to-use or when-not-to-use context.

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

Deploy Server