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

Extends:

public options

Uses:

list
term_io
uri_template(Representation)
user

Remarks:

(none)

Inherited public predicates:

check_option/1 check_options/1 default_option/1 default_options/1 option/2 option/3 valid_option/1 valid_options/1

Public predicates 

`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 

`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

`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

`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)

`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

`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

`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

`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

`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

`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

`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

`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

`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

`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

`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

`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

`pairs_to_curly/2`

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

Compilation flags:

static

Template:

pairs_to_curly(Pairs,Curly)

Mode and number of proofs:

pairs_to_curly(+list,-compound) - one

Private predicates 

(no local declarations; see entity ancestors if any)

Operators 

(none)

mcp_server_application

`mcp_server_application`