docs: add MCP tool configuration documentation

docs/tools_configuration.md

@@ -8,6 +8,7 @@ PicoClaw's tools configuration is located in the `tools` field of `config.json`.
 {
   "tools": {
     "web": { ... },
+    "mcp": { ... },
     "exec": { ... },
     "cron": { ... },
     "skills": { ... }
@@ -22,7 +23,7 @@ Web tools are used for web search and fetching.
 ### Brave
 
 | Config        | Type   | Default | Description               |
-|--------|------|---------|-------------|
+| ------------- | ------ | ------- | ------------------------- |
 | `enabled`     | bool   | false   | Enable Brave search       |
 | `api_key`     | string | -       | Brave Search API key      |
 | `max_results` | int    | 5       | Maximum number of results |
@@ -30,14 +31,14 @@ Web tools are used for web search and fetching.
 ### DuckDuckGo
 
 | Config        | Type | Default | Description               |
-|--------|------|---------|-------------|
+| ------------- | ---- | ------- | ------------------------- |
 | `enabled`     | bool | true    | Enable DuckDuckGo search  |
 | `max_results` | int  | 5       | Maximum number of results |
 
 ### Perplexity
 
 | Config        | Type   | Default | Description               |
-|--------|------|---------|-------------|
+| ------------- | ------ | ------- | ------------------------- |
 | `enabled`     | bool   | false   | Enable Perplexity search  |
 | `api_key`     | string | -       | Perplexity API key        |
 | `max_results` | int    | 5       | Maximum number of results |
@@ -47,7 +48,7 @@ Web tools are used for web search and fetching.
 The exec tool is used to execute shell commands.
 
 | Config                 | Type  | Default | Description                                |
-|--------|------|---------|-------------|
+| ---------------------- | ----- | ------- | ------------------------------------------ |
 | `enable_deny_patterns` | bool  | true    | Enable default dangerous command blocking  |
 | `custom_deny_patterns` | array | []      | Custom deny patterns (regular expressions) |
 
@@ -80,10 +81,7 @@ By default, PicoClaw blocks the following dangerous commands:
   "tools": {
     "exec": {
       "enable_deny_patterns": true,
-      "custom_deny_patterns": [
+      "custom_deny_patterns": ["\\brm\\s+-r\\b", "\\bkillall\\s+python"]
-        "\\brm\\s+-r\\b",
-        "\\bkillall\\s+python"
-      ]
     }
   }
 }
@@ -94,9 +92,84 @@ By default, PicoClaw blocks the following dangerous commands:
 The cron tool is used for scheduling periodic tasks.
 
 | Config                 | Type | Default | Description                                    |
-|--------|------|---------|-------------|
+| ---------------------- | ---- | ------- | ---------------------------------------------- |
 | `exec_timeout_minutes` | int  | 5       | Execution timeout in minutes, 0 means no limit |
 
+## MCP Tool
+
+The MCP tool enables integration with external Model Context Protocol servers.
+
+### Global Config
+
+| Config    | Type   | Default | Description                         |
+| --------- | ------ | ------- | ----------------------------------- |
+| `enabled` | bool   | false   | Enable MCP integration globally     |
+| `servers` | object | `{}`    | Map of server name to server config |
+
+### Per-Server Config
+
+| Config     | Type   | Required | Description                                |
+| ---------- | ------ | -------- | ------------------------------------------ |
+| `enabled`  | bool   | yes      | Enable this MCP server                     |
+| `type`     | string | no       | Transport type: `stdio`, `sse`, `http`     |
+| `command`  | string | stdio    | Executable command for stdio transport     |
+| `args`     | array  | no       | Command arguments for stdio transport      |
+| `env`      | object | no       | Environment variables for stdio process    |
+| `env_file` | string | no       | Path to environment file for stdio process |
+| `url`      | string | sse/http | Endpoint URL for `sse`/`http` transport    |
+| `headers`  | object | no       | HTTP headers for `sse`/`http` transport    |
+
+### Transport Behavior
+
+- If `type` is omitted, transport is auto-detected:
+  - `url` is set → `sse`
+  - `command` is set → `stdio`
+- `http` and `sse` both use `url` + optional `headers`.
+- `env` and `env_file` are only applied to `stdio` servers.
+
+### Configuration Examples
+
+#### 1) Stdio MCP server
+
+```json
+{
+  "tools": {
+    "mcp": {
+      "enabled": true,
+      "servers": {
+        "filesystem": {
+          "enabled": true,
+          "command": "npx",
+          "args": ["-y", "@modelcontextprotocol/server-filesystem", "/tmp"]
+        }
+      }
+    }
+  }
+}
+```
+
+#### 2) Remote SSE/HTTP MCP server
+
+```json
+{
+  "tools": {
+    "mcp": {
+      "enabled": true,
+      "servers": {
+        "remote-mcp": {
+          "enabled": true,
+          "type": "sse",
+          "url": "https://example.com/mcp",
+          "headers": {
+            "Authorization": "Bearer YOUR_TOKEN"
+          }
+        }
+      }
+    }
+  }
+}
+```
+
 ## Skills Tool
 
 The skills tool configures skill discovery and installation via registries like ClawHub.
@@ -104,7 +177,7 @@ The skills tool configures skill discovery and installation via registries like
 ### Registries
 
 | Config                             | Type   | Default              | Description             |
-|--------|------|---------|-------------|
+| ---------------------------------- | ------ | -------------------- | ----------------------- |
 | `registries.clawhub.enabled`       | bool   | true                 | Enable ClawHub registry |
 | `registries.clawhub.base_url`      | string | `https://clawhub.ai` | ClawHub base URL        |
 | `registries.clawhub.search_path`   | string | `/api/v1/search`     | Search API path         |
@@ -136,8 +209,10 @@ The skills tool configures skill discovery and installation via registries like
 All configuration options can be overridden via environment variables with the format `PICOCLAW_TOOLS_<SECTION>_<KEY>`:
 
 For example:
+
 - `PICOCLAW_TOOLS_WEB_BRAVE_ENABLED=true`
 - `PICOCLAW_TOOLS_EXEC_ENABLE_DENY_PATTERNS=false`
 - `PICOCLAW_TOOLS_CRON_EXEC_TIMEOUT_MINUTES=10`
+- `PICOCLAW_TOOLS_MCP_ENABLED=true`
 
-Note: Array-type environment variables are not currently supported and must be set via the config file.
+Note: Nested map-style config (for example `tools.mcp.servers.<name>.*`) is configured in `config.json` rather than environment variables.