.. index:: single: mcp_server_application .. _mcp_server_application/0:

.. rst-class:: right

category

`mcp_server_application`

Common predicates for MCP servers: tool/prompt/resource descriptor conversion, completion request handling, schema derivation from info/2 and mode/2 directives, auto-dispatch, canonical complete-result terms, curly-term predicates, and MCP Apps (_meta.ui) metadata.

| Availability: | logtalk_load(mcp_server(loader))

| Author: Paulo Moura | Version: 1:0:0 | Date: 2026-09-07

| Compilation flags: | static

| Remarks: | (none)

| Inherited public predicates: | Â :ref:`options_protocol/0::check_option/1` Â :ref:`options_protocol/0::check_options/1` Â :ref:`options_protocol/0::default_option/1` Â :ref:`options_protocol/0::default_options/1` Â :ref:`options_protocol/0::option/2` Â :ref:`options_protocol/0::option/3` Â :ref:`options_protocol/0::valid_option/1` Â :ref:`options_protocol/0::valid_options/1` Â

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

Public predicates

.. index:: tool_descriptors_to_json/3 .. _mcp_server_application/0::tool_descriptors_to_json/3:

tool_descriptors_to_json/3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts a list of tool(Name, Functor, Arity) descriptors into MCP JSON tool definitions, deriving titles, descriptions and input schemas from the application object's info/2 and mode/2 directives.

| Compilation flags: | static

| Template: | tool_descriptors_to_json(ToolDescriptors,Application,JsonTools) | Mode and number of proofs: | tool_descriptors_to_json(+list,+object_identifier,-list) - one

Protected predicates

.. index:: prompt_descriptors_to_json/2 .. _mcp_server_application/0::prompt_descriptors_to_json/2:

prompt_descriptors_to_json/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts prompt descriptors (3-arg or 4-arg) into MCP JSON prompt definitions.

| Compilation flags: | static

| Template: | prompt_descriptors_to_json(PromptDescriptors,JsonPrompts) | Mode and number of proofs: | prompt_descriptors_to_json(+list,-list) - one

.. index:: resource_descriptors_to_json/3 .. _mcp_server_application/0::resource_descriptors_to_json/3:

resource_descriptors_to_json/3 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts resource descriptors (4-arg or 5-arg) into MCP JSON resource definitions. When the application defines resource_ui_meta/2, attaches _meta.ui (MCP Apps).

| Compilation flags: | static

| Template: | resource_descriptors_to_json(Descriptors,Application,Resources) | Mode and number of proofs: | resource_descriptors_to_json(+list,+object_identifier,-list) - one

.. index:: resource_template_descriptors_to_json/2 .. _mcp_server_application/0::resource_template_descriptors_to_json/2:

resource_template_descriptors_to_json/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts resource template descriptors (4-arg or 5-arg) into MCP JSON resource template definitions. No partial list is returned when a descriptor is invalid.

| Compilation flags: | static

| Template: | resource_template_descriptors_to_json(Descriptors,ResourceTemplates) | Mode and number of proofs: | resource_template_descriptors_to_json(+list,-list) - one_or_error

| Exceptions: | A descriptor contains an invalid RFC 6570 URI template URITemplate: | domain_error(uri_template,URITemplate)

.. index:: application_resource_template_uri/2 .. _mcp_server_application/0::application_resource_template_uri/2:

application_resource_template_uri/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Checks that a concrete resource URI matches the literal segments of one of the application resource templates. Full RFC 6570 expression validation and authorization remain application responsibilities.

| Compilation flags: | static

| Template: | application_resource_template_uri(Application,URI) | Mode and number of proofs: | application_resource_template_uri(+object_identifier,+atom) - zero_or_one

.. index:: completion_request/5 .. _mcp_server_application/0::completion_request/5:

completion_request/5 ^^^^^^^^^^^^^^^^^^^^^^^^

Validates and normalizes completion request parameters. The normalized reference is prompt(Name) or resource(URI), the argument is a Name-PartialValue pair, and the context is a list of prior argument pairs.

| Compilation flags: | static

| Template: | completion_request(Application,Params,Reference,Argument,Context) | Mode and number of proofs: | completion_request(+object_identifier,+compound,-compound,-pair,-list) - zero_or_one

.. index:: completion_result_to_json/2 .. _mcp_server_application/0::completion_result_to_json/2:

completion_result_to_json/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Validates and converts a completion result to its MCP JSON curly-term representation.

| Compilation flags: | static

| Template: | completion_result_to_json(Result,JsonCompletion) | Mode and number of proofs: | completion_result_to_json(+compound,-compound) - zero_or_one

.. index:: auto_dispatch_tool/5 .. _mcp_server_application/0::auto_dispatch_tool/5:

auto_dispatch_tool/5 ^^^^^^^^^^^^^^^^^^^^^^^^

Auto-dispatches a tool call by calling the predicate on the application, collecting output-mode arguments, and returning structured output with a backwards-compatible text content item.

| Compilation flags: | static

| Template: | auto_dispatch_tool(Application,Functor,Arity,ToolArguments,Result) | Mode and number of proofs: | auto_dispatch_tool(+object_identifier,+atom,+integer,+compound,-compound) - one

.. index:: try_tool_call_3/7 .. _mcp_server_application/0::try_tool_call_3/7:

try_tool_call_3/7 ^^^^^^^^^^^^^^^^^^^^^

Tries tool_call/3. Falls back to auto-dispatch on failure.

| Compilation flags: | static

| Template: | try_tool_call_3(Application,ToolName,Functor,Arity,ArgPairs,ToolArguments,Result) | Mode and number of proofs: | try_tool_call_3(+object_identifier,+atom,+atom,+integer,+list,+compound,-compound) - one

.. index:: tool_input_schema/4 .. _mcp_server_application/0::tool_input_schema/4:

tool_input_schema/4 ^^^^^^^^^^^^^^^^^^^^^^^

Derives a JSON Schema curly-term for tool input arguments from the application object's info/2 and mode/2 directives. Used by Streamable HTTP x-mcp-header / Mcp-Param-* validation when the application does not define input_schema/2.

| Compilation flags: | static

| Template: | tool_input_schema(Application,Functor,Arity,InputSchema) | Mode and number of proofs: | tool_input_schema(+object_identifier,+atom,+integer,-compound) - one

.. index:: tool_output_schema/4 .. _mcp_server_application/0::tool_output_schema/4:

tool_output_schema/4 ^^^^^^^^^^^^^^^^^^^^^^^^

Derives a JSON Schema curly-term for tool output arguments from the application object's info/2 and mode/2 directives.

| Compilation flags: | static

| Template: | tool_output_schema(Application,Functor,Arity,OutputSchema) | Mode and number of proofs: | tool_output_schema(+object_identifier,+atom,+integer,-compound) - one

.. index:: format_content_items/2 .. _mcp_server_application/0::format_content_items/2:

format_content_items/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts canonical content item terms into MCP JSON content array elements.

| Compilation flags: | static

| Template: | format_content_items(Items,Elements) | Mode and number of proofs: | format_content_items(+list,-list) - one

.. index:: format_prompt_messages/2 .. _mcp_server_application/0::format_prompt_messages/2:

format_prompt_messages/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts message(Role, text(Text)) terms into MCP JSON prompt message objects.

| Compilation flags: | static

| Template: | format_prompt_messages(Messages,JsonMessages) | Mode and number of proofs: | format_prompt_messages(+list,-list) - one

.. index:: format_resource_contents/2 .. _mcp_server_application/0::format_resource_contents/2:

format_resource_contents/2 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Converts text_content/3 and blob_content/3 terms into MCP JSON resource content objects.

| Compilation flags: | static

| Template: | format_resource_contents(Contents,JsonContents) | Mode and number of proofs: | format_resource_contents(+list,-list) - one

.. index:: has_pair/3 .. _mcp_server_application/0::has_pair/3:

has_pair/3 ^^^^^^^^^^^^^^

Looks up a Key-Value pair inside a curly-term.

| Compilation flags: | static

| Template: | has_pair(Curly,Key,Value) | Mode and number of proofs: | has_pair(+compound,+atom,?term) - zero_or_one

.. index:: curly_to_pairs/2 .. _mcp_server_application/0::curly_to_pairs/2:

curly_to_pairs/2 ^^^^^^^^^^^^^^^^^^^^

Converts a curly-term to a list of Key-Value pairs.

| Compilation flags: | static

| Template: | curly_to_pairs(Curly,Pairs) | Mode and number of proofs: | curly_to_pairs(+compound,-list) - one

.. index:: pairs_to_curly/2 .. _mcp_server_application/0::pairs_to_curly/2:

pairs_to_curly/2 ^^^^^^^^^^^^^^^^^^^^