feat(config): add configurable prompts support (#559)

Enable administrators to define custom MCP prompts in config.toml
using template substitution with {{argument}} syntax.

- PromptLoader for loading prompts from TOML config
- Core prompt types (ServerPrompt, Prompt, PromptArgument, PromptMessage)
- Template argument substitution with {{variable}} syntax
- Required argument validation
- Integration with MCP server to register and serve config prompts

Signed-off-by: Nader Ziada <[email protected]>

Author: nader-ziada

README.md

@@ -292,6 +292,27 @@ vim /etc/kubernetes-mcp-server/conf.d/99-local.toml
 pkill -HUP kubernetes-mcp-server
 ```
 
+### MCP Prompts
+
+The server supports MCP prompts for workflow templates. Define custom prompts in `config.toml`:
+
+```toml
+[[prompts]]
+name = "my-workflow"
+title = "my workflow"
+description = "Custom workflow"
+
+[[prompts.arguments]]
+name = "resource_name"
+required = true
+
+[[prompts.messages]]
+role = "user"
+content = "Help me with {{resource_name}}"
+```
+
+See docs/PROMPTS.md for detailed documentation.
+
 ## 🛠️ Tools and Functionalities <a id="tools-and-functionalities"></a>
 
 The Kubernetes MCP server supports enabling or disabling specific groups of tools and functionalities (tools, resources, prompts, and so on) via the `--toolsets` command-line flag or `toolsets` configuration option.

docs/PROMPTS.md

@@ -0,0 +1,62 @@
+# MCP Prompts Support
+
+The Kubernetes MCP Server supports [MCP Prompts](https://modelcontextprotocol.io/docs/concepts/prompts), which provide pre-defined workflow templates and guidance to AI assistants.
+
+## What are MCP Prompts?
+
+MCP Prompts are pre-defined templates that guide AI assistants through specific workflows. They combine:
+- **Structured guidance**: Step-by-step instructions for common tasks
+- **Parameterization**: Arguments that customize the prompt for specific contexts
+- **Conversation templates**: Pre-formatted messages that guide the interaction
+
+## Creating Custom Prompts
+
+Define custom prompts in your `config.toml` file - no code changes or recompilation needed!
+
+### Example
+
+```toml
+[[prompts]]
+name = "check-pod-logs"
+title = "Check Pod Logs"
+description = "Quick way to check pod logs"
+
+[[prompts.arguments]]
+name = "pod_name"
+description = "Name of the pod"
+required = true
+
+[[prompts.arguments]]
+name = "namespace"
+description = "Namespace of the pod"
+required = false
+
+[[prompts.messages]]
+role = "user"
+content = "Show me the logs for pod {{pod_name}} in {{namespace}}"
+
+[[prompts.messages]]
+role = "assistant"
+content = "I'll retrieve and analyze the logs for you."
+```
+
+## Configuration Reference
+
+### Prompt Fields
+- **name** (required): Unique identifier for the prompt
+- **title** (optional): Human-readable display name
+- **description** (required): Brief explanation of what the prompt does
+- **arguments** (optional): List of parameters the prompt accepts
+- **messages** (required): Conversation template with role/content pairs
+
+### Argument Fields
+- **name** (required): Argument identifier
+- **description** (optional): Explanation of the argument's purpose
+- **required** (optional): Whether the argument must be provided (default: false)
+
+### Argument Substitution
+Use `{{argument_name}}` placeholders in message content. The template engine replaces these with actual values when the prompt is called.
+
+## Configuration File Location
+
+Place your prompts in the `config.toml` file used by the MCP server. Specify the config file path using the `--config` flag when starting the server.

go.mod

@@ -16,6 +16,7 @@ require (
 	github.com/stretchr/testify v1.11.1
 	golang.org/x/oauth2 v0.34.0
 	golang.org/x/sync v0.19.0
+	gopkg.in/yaml.v3 v3.0.1
 	helm.sh/helm/v3 v3.19.3
 	k8s.io/api v0.34.3
 	k8s.io/apiextensions-apiserver v0.34.3
@@ -133,7 +134,6 @@ require (
 	google.golang.org/protobuf v1.36.6 // indirect
 	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
-	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/apiserver v0.34.3 // indirect
 	k8s.io/component-base v0.34.3 // indirect
 	k8s.io/kube-openapi v0.0.0-20250710124328-f3f2b991d03b // indirect