add_pet
Add a new pet to the store. [POST /pet]
LABSCO SUMMARY
The tool list is the API's own operation list, so what can be called is exactly what the specification declares.
Every tool carries its HTTP method and path in its description, which makes the mapping back to the endpoint visible instead of something you infer from the name. Because the surface is generated from a specification handed in at startup, the tools captured here belong to the Swagger Petstore demo — pets, store orders and users — rather than to the server itself. What the generation inherits is worth noticing: the write operations are as real as the API behind them, and delete_pet, delete_order and delete_user sit in the same list as the reads, with no separate switch in front of them.
What it is
A tool surface generated from an OpenAPI specification supplied when the server starts: every operation becomes a tool named after it and labelled with its method and path. The specification behind this capture is the Swagger Petstore.
What you get
- The pet resource end to end: add_pet and update_pet, find_pets_by_status and find_pets_by_tags, get_pet_by_id, update_pet_with_form, delete_pet, and upload_file for an image.
- The store side: get_inventory for pet inventories by status, place_order, get_order_by_id and delete_order.
- User management: create_user, create_users_with_list_input, get_user_by_name, update_user and delete_user, alongside login_user and logout_user.
- Each tool's HTTP method and path stated in its own description, so a call traces back to the endpoint it hits without a separate mapping.
- Parameters taken straight from the specification's operation — delete_pet takes the api_key the spec defines alongside the petId, and update_pet_with_form takes the form fields rather than a body.
Requirements
An OpenAPI specification for the server to generate its tools from, supplied when it starts; the capture here points at the Swagger Petstore. Whatever the API behind it requires — login_user exchanges a username and password, and delete_pet takes an api_key.
Setup effort
One command — npx mcp-openapi --spec https://petstore3.swagger.io/api/v3/openapi.json
USE CASES
01
Managing the catalogue behind a storefront
Creating, editing and removing an item are separate operations generated from the specification, including a form-data update and a separate image upload, each labelled with the method and path it hits.
02
Finding what is in stock and how much of it
Items are searchable by status or by tag, one is retrievable by id, and the store's own inventory count groups the totals by status.
03
Placing an order and following it afterwards
The order carries the item, quantity, ship date and completion flag on creation, and is then retrievable and removable by its own identifier.
04
Running the accounts on the other side of the API
Users are created one at a time or from an array, addressed afterwards by username rather than by id, and the session tools log one in and out.
19 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
create_user
Create user. [POST /user]
create_users_with_list_input
Creates list of users with given input array. [POST /user/createWithList]
delete_order
Delete purchase order by identifier. [DELETE /store/order/{orderId}]
delete_pet
Deletes a pet. [DELETE /pet/{petId}]
delete_user
Delete user resource. [DELETE /user/{username}]
find_pets_by_status
Finds Pets by status. [GET /pet/findByStatus]
find_pets_by_tags
Finds Pets by tags. [GET /pet/findByTags]
get_inventory
Returns pet inventories by status. [GET /store/inventory]
get_order_by_id
Find purchase order by ID. [GET /store/order/{orderId}]
get_pet_by_id
Find pet by ID. [GET /pet/{petId}]
get_user_by_name
Get user by user name. [GET /user/{username}]
login_user
Logs user into the system. [GET /user/login]
logout_user
Logs out current logged in user session. [GET /user/logout]
place_order
Place an order for a pet. [POST /store/order]
update_pet
Update an existing pet. [PUT /pet]
update_pet_with_form
Updates a pet in the store with form data. [POST /pet/{petId}]
update_user
Update user resource. [PUT /user/{username}]
upload_file
Uploads an image. [POST /pet/{petId}/uploadImage]
BEFORE YOU INSTALL
What to know first
Tools you get
19 tools when we connected. Tools are generated from your OpenAPI spec; this count reflects the Swagger Petstore demo. --include, --exclude and --prefix shape the list, and --dynamic-discovery, automatic for specs with 100+ endpoints, replaces it with three meta-tools.
Requires
- npx on PATH
- Node.js 18 or later
Where it runs
All 3 documented setups run the server on your machine.
CONTEXT COST
Light Standing cost
Rated by the size of the 19 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Server setup
TERMINAL
npx mcp-openapi --spec https://petstore3.swagger.io/api/v3/openapi.jsonMCP Clients
Claude Desktop — no auth
CLAUDE DESKTOP — NO AUTH · JSON
{
"mcpServers": {
"petstore": {
"command": "npx",
"args": [
"mcp-openapi",
"--spec",
"https://petstore3.swagger.io/api/v3/openapi.json"
]
}
}
}Claude Desktop — bearer token
CLAUDE DESKTOP — BEARER TOKEN · JSON
{
"mcpServers": {
"github": {
"command": "npx",
"args": [
"mcp-openapi",
"--spec",
"https://raw.githubusercontent.com/github/rest-api-description/main/descriptions/api.github.com/api.github.com.json",
"--auth-type",
"bearer",
"--auth-token",
"$GITHUB_TOKEN",
"--prefix",
"github",
"--include",
"listReposForAuthenticatedUser,getRepo,listIssues,createIssue"
],
"env": {
"GITHUB_TOKEN": "<YOUR_GITHUB_TOKEN>"
}
}
}
}The README's bearer-token example, wired to GitHub's REST API: <YOUR_GITHUB_TOKEN> is your GitHub token. For your own API, the --spec URL, token and --include list are that API's.
Claude Desktop — API key
CLAUDE DESKTOP — API KEY · JSON
{
"mcpServers": {
"weather": {
"command": "npx",
"args": [
"mcp-openapi",
"--spec",
"<YOUR_WEATHER_URL>/openapi.json",
"--auth-type",
"api-key",
"--auth-name",
"X-API-Key",
"--auth-value",
"$WEATHER_API_KEY",
"--auth-in",
"header"
],
"env": {
"WEATHER_API_KEY": "<YOUR_WEATHER_API_KEY>"
}
}
}
}An illustration from the README: api.weather.example.com is not a real API. Point --spec at your own API's OpenAPI document, and set --auth-name and WEATHER_API_KEY to the header name and key that API expects.
