.. index:: single: mcp_prompt_protocol
.. _mcp_prompt_protocol/0:

.. rst-class:: right

**protocol**

``mcp_prompt_protocol``
=======================

Protocol for Logtalk objects that provide prompts to be exposed via an MCP (Model Context Protocol) server. Implements the MCP 2025-06-18 specification. Implementing objects must define the set of prompts available and handle prompt get requests. Prompts are templates for structured LLM interactions that can accept arguments to customize their behavior.

| **Availability:** 
|    ``logtalk_load(mcp_server(loader))``

| **Author:** Paulo Moura
| **Version:** 0:2:0
| **Date:** 2026-02-24

| **Compilation flags:**
|    ``static``


| **Dependencies:**
|   (none)


| **Remarks:**

   - Capabilities: Objects providing prompts must declare ``prompts`` in their ``capabilities/1`` predicate (from the ``mcp_tool_protocol`` protocol). The server will then advertise the ``prompts`` capability and handle ``prompts/list`` and ``prompts/get`` requests.
   - Prompt descriptors: Each prompt is described by a ``prompt(Name, Description, Arguments)`` or ``prompt(Name, Title, Description, Arguments)`` term where ``Name`` is an atom, ``Title`` is an optional human-friendly display name (an atom), ``Description`` is a human-readable atom, and ``Arguments`` is a list of ``argument(ArgName, ArgDescription, Required)`` terms.
   - Prompt messages: The ``prompt_get/3`` predicate must return a result term containing a list of messages. Each message is a ``message(Role, Content)`` term where ``Role`` is ``user`` or ``assistant`` and ``Content`` is ``text(Text)`` where ``Text`` is an atom.

| **Inherited public predicates:**
|    (none)

.. contents::
   :local:
   :backlinks: top

Public predicates
-----------------

.. index:: prompts/1
.. _mcp_prompt_protocol/0::prompts/1:

``prompts/1``
^^^^^^^^^^^^^

Returns a list of prompt descriptors available from this object. Each descriptor is a compound term ``prompt(Name, Description, Arguments)`` or ``prompt(Name, Title, Description, Arguments)`` where ``Name`` is the MCP prompt name (an atom), ``Title`` is an optional human-friendly display name (an atom), ``Description`` is a human-readable description (an atom), and ``Arguments`` is a list of ``argument(ArgName, ArgDescription, Required)`` terms describing the prompt arguments. ``ArgName`` and ``ArgDescription`` are atoms, and ``Required`` is the boolean ``true`` or ``false``.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``prompts(Prompts)``
| **Mode and number of proofs:**
|    ``prompts(-list(compound))`` - ``one``


------------

.. index:: prompt_get/3
.. _mcp_prompt_protocol/0::prompt_get/3:

``prompt_get/3``
^^^^^^^^^^^^^^^^

Handles a prompt get request. ``Name`` is the MCP prompt name (as declared in ``prompts/1``), ``Arguments`` is a list of ``ArgumentName-Value`` pairs provided by the client, and ``Result`` is unified with the prompt result. The result must be one of: ``messages(MessageList)`` for a list of prompt messages, or ``messages(Description, MessageList)`` to also include a description. Each message in the list must be a ``message(Role, Content)`` term where ``Role`` is ``user`` or ``assistant`` and ``Content`` is ``text(Text)`` where ``Text`` is an atom.

| **Compilation flags:**
|    ``static``

| **Template:**
|    ``prompt_get(Name,Arguments,Result)``
| **Mode and number of proofs:**
|    ``prompt_get(+atom,+list(pair),--compound)`` - ``one``


------------

Protected predicates
--------------------

(none)

Private predicates
------------------

(none)

Operators
---------

(none)