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Prompts

As explained in Why reShapr?, reShapr can create secure MCP servers in seconds without coding, just by importing your API’s existing artifacts - like OpenAPI 3.x specs, GraphQL schemas and gRPC/Protobuf definitions. These artifacts are directly used to produce MCP Tools that are at the core of the Model Context Protocol. Another interesting aspect of MCP is that it may be composed of MCP Resources and MCP Prompts. While MCP Tools are often enough for practical use of MCP, all these capabilities are likely to be part of a complete and production ready MCP Server.

Contrary to tools, prompts can’t - and shouldn’t - be directly inferred from an API contract. They should be designed to provide users with accelerators on how to interact with the model, offer additional instructions and guardrails on how to use tools for a specific use case, or provide additional details on how to orchestrate tool calls.

reShapr provides an easy way to design and specify your Prompts using a simple YAML description, called the Prompts specification. If you want to provide such prompts to your reShapr-powered MCP endpoint, you’ll need to write this simple file and attach it to your existing Service. Let’s see a simple example of such a file:

apiVersion: reshapr.io/v1alpha1
kind: Prompts
service:
  name: Petstore
  version: 1.0.0
prompts:
  list_pets:
    title: List the pets
    description: Browse the catalog to get all the pets
    result: Get all the pets from the catalog
  get_pet:
    title: Get details of a pet with its name
    description: Get details for a specific pet from the catalog
    arguments:
      - name: name
        description: The name of the pet to retrieve
        required: true
    result: |-
      Get the detailed information on the pet named '${name}'.
      The MCP tool to call is 'get_pet_by_name', using '${name}' as the tool argument called 'name'.

A Prompts artifact follows some simple rules:

  • It always contain an identification section made of apiVersion and kind properties that must have the reshapr.io/v1alpha1 and Prompts values respectively,
  • It must be bound to a specific reShapr Service using the service.name and service.version properties which values must match an already discovered Service,
  • The prompts section then defines the prompts:
    • We have 2 prompts here: list_pets and get_pet
    • A prompt must always have a result which will be returned to the model when called,
    • A prompt may provide optional title and description to provide more context to the user when choosing an appropriate prompt,
    • A prompt may also provide arguments that allow the production of a customized result prompt message, where the user provides its contextuel values for each argument.

In the case of prompt using arguments, the result value can be expressed using ${} expressions that will be replaced by user provided values. Typically in our example, if user is looking for a pet named Rusty, the prompt will be generated with Rusty in the place of the ${name} placeholder.

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