MCP

VEF has first-class support for MCP (Model Context Protocol) server integration.

Runtime Behavior

The MCP module is always part of the boot sequence, but the MCP server only activates when:

Config	Meaning
vef.mcp.enabled = true	MCP server and endpoint become active

When enabled, the HTTP endpoint is mounted at:

/mcp

What The Module Provides

When enabled, the MCP module provides:

Runtime piece	Meaning
MCP server construction	builds the MCP server instance
HTTP handler	adapts the MCP server to HTTP
app middleware	mounts /mcp into the Fiber app
built-in tool	database_query
built-in prompts	data-dict-assistant, naming-master

The module does not currently ship built-in static MCP resources or built-in resource templates.

Public Provider Interfaces

The public mcp package exposes these provider interfaces:

Interface	Purpose
mcp.ToolProvider	register MCP tools
mcp.ResourceProvider	register static MCP resources
mcp.ResourceTemplateProvider	register MCP resource templates
mcp.PromptProvider	register MCP prompts

Supporting definition types:

Type	Purpose
mcp.ToolDefinition	tool + handler
mcp.ResourceDefinition	static resource + handler
mcp.ResourceTemplateDefinition	resource template + handler
mcp.PromptDefinition	prompt + handler
mcp.ServerInfo	server name, version, and instructions

Dependency-Injection Extension Points

Applications can register custom MCP capabilities through:

Helper	Registers into
vef.ProvideMCPTools(...)	vef:mcp:tools
vef.ProvideMCPResources(...)	vef:mcp:resources
vef.ProvideMCPResourceTemplates(...)	vef:mcp:templates
vef.ProvideMCPPrompts(...)	vef:mcp:prompts
vef.SupplyMCPServerInfo(...)	optional server info override

Built-In Tool: database_query

The built-in MCP tool currently exposed by the framework is:

Tool name	Purpose
database_query	execute a parameterized SQL query and return JSON rows

Input arguments:

Argument	Meaning
sql	SQL query string using ? placeholders
params	optional positional parameters

Behavior notes:

• results are returned as JSON text content
• UTF-8 byte slices are converted to strings before JSON encoding
• the query runs through mcp.DBWithOperator(...), so the current MCP principal is bound as the operator when possible

Built-In Prompts

The framework currently registers these built-in prompts:

Prompt name	Purpose
data-dict-assistant	data dictionary management assistant
naming-master	naming assistant for code and database naming

Schema Helpers

The public mcp package also provides JSON Schema helpers for MCP tool and prompt contracts:

Helper	Purpose
mcp.SchemaFor[T]()	generate schema from a generic type
mcp.SchemaOf(v)	generate schema from a runtime value
mcp.MustSchemaFor[T]()	panic-on-error schema generation
mcp.MustSchemaOf(v)	panic-on-error schema generation

These helpers are suitable for tool input schemas.

Authentication

When vef.mcp.require_auth = true, the HTTP handler applies Bearer-token verification through the application auth manager.

That matters because the built-in database_query tool can already inspect live database state.

Minimal Example

package appmcp

import (
  "github.com/coldsmirk/vef-framework-go"
  "github.com/coldsmirk/vef-framework-go/mcp"
)

var Module = vef.Module(
  "app:mcp",
  vef.ProvideMCPTools(NewToolProvider),
  vef.SupplyMCPServerInfo(&mcp.ServerInfo{
    Name:         "my-app",
    Version:      "v1.0.0",
    Instructions: "Internal assistant surface for My App",
  }),
)

In many apps, the first step is even smaller:

var Module = vef.Module(
  "app:mcp",
  vef.ProvideMCPTools(NewToolProvider),
)

What To Document For Your Own App

If you expose custom MCP features, document:

• which tools are registered
• whether auth is required
• which domain data your resources or prompts expose
• whether any prompt or tool performs side effects

Next Step

Read Extension Points for the full list of MCP-related DI groups and helpers.