feat(mcp-config): add list of disabled_tools (#1533)

README.md

@@ -275,6 +275,7 @@ using `$(echo $VAR)` syntax.
       "args": ["/path/to/mcp-server.js"],
       "timeout": 120,
       "disabled": false,
+      "disabled_tools": ["some-tool-name"],
       "env": {
         "NODE_ENV": "production"
       }
@@ -284,6 +285,7 @@ using `$(echo $VAR)` syntax.
       "url": "https://api.githubcopilot.com/mcp/",
       "timeout": 120,
       "disabled": false,
+      "disabled_tools": ["create_issue", "create_pull_request"],
       "headers": {
         "Authorization": "Bearer $GH_PAT"
       }
@@ -335,6 +337,26 @@ permissions. Use this with care.
 You can also skip all permission prompts entirely by running Crush with the
 `--yolo` flag. Be very, very careful with this feature.
 
+### Disabling Built-In Tools
+
+If you'd like to prevent Crush from using certain built-in tools entirely, you
+can disable them via the `options.disabled_tools` list. Disabled tools are
+completely hidden from the agent.
+
+```json
+{
+  "$schema": "https://charm.land/crush.json",
+  "options": {
+    "disabled_tools": [
+      "bash",
+      "sourcegraph"
+    ]
+  }
+}
+```
+
+To disable tools from MCP servers, see the [MCP config section](#mcps).
+
 ### Initialization
 
 When you initialize a project, Crush analyzes your codebase and creates

internal/agent/coordinator.go

@@ -388,6 +388,12 @@ func (c *coordinator) buildTools(ctx context.Context, agent config.Agent) ([]fan
 	}
 
 	for _, tool := range tools.GetMCPTools(c.permissions, c.cfg.WorkingDir()) {
+		// Check MCP-specific disabled tools.
+		if mcpCfg, ok := c.cfg.MCP[tool.MCP()]; ok {
+			if slices.Contains(mcpCfg.DisabledTools, tool.MCPToolName()) {
+				continue
+			}
+		}
 		if agent.AllowedMCP == nil {
 			// No MCP restrictions
 			filteredTools = append(filteredTools, tool)

internal/config/config.go

@@ -144,13 +144,14 @@ const (
 )
 
 type MCPConfig struct {
-	Command  string            `json:"command,omitempty" jsonschema:"description=Command to execute for stdio MCP servers,example=npx"`
-	Env      map[string]string `json:"env,omitempty" jsonschema:"description=Environment variables to set for the MCP server"`
-	Args     []string          `json:"args,omitempty" jsonschema:"description=Arguments to pass to the MCP server command"`
-	Type     MCPType           `json:"type" jsonschema:"required,description=Type of MCP connection,enum=stdio,enum=sse,enum=http,default=stdio"`
-	URL      string            `json:"url,omitempty" jsonschema:"description=URL for HTTP or SSE MCP servers,format=uri,example=http://localhost:3000/mcp"`
-	Disabled bool              `json:"disabled,omitempty" jsonschema:"description=Whether this MCP server is disabled,default=false"`
-	Timeout  int               `json:"timeout,omitempty" jsonschema:"description=Timeout in seconds for MCP server connections,default=15,example=30,example=60,example=120"`
+	Command       string            `json:"command,omitempty" jsonschema:"description=Command to execute for stdio MCP servers,example=npx"`
+	Env           map[string]string `json:"env,omitempty" jsonschema:"description=Environment variables to set for the MCP server"`
+	Args          []string          `json:"args,omitempty" jsonschema:"description=Arguments to pass to the MCP server command"`
+	Type          MCPType           `json:"type" jsonschema:"required,description=Type of MCP connection,enum=stdio,enum=sse,enum=http,default=stdio"`
+	URL           string            `json:"url,omitempty" jsonschema:"description=URL for HTTP or SSE MCP servers,format=uri,example=http://localhost:3000/mcp"`
+	Disabled      bool              `json:"disabled,omitempty" jsonschema:"description=Whether this MCP server is disabled,default=false"`
+	DisabledTools []string          `json:"disabled_tools,omitempty" jsonschema:"description=List of tools from this MCP server to disable,example=get-library-doc"`
+	Timeout       int               `json:"timeout,omitempty" jsonschema:"description=Timeout in seconds for MCP server connections,default=15,example=30,example=60,example=120"`
 
 	// TODO: maybe make it possible to get the value from the env
 	Headers map[string]string `json:"headers,omitempty" jsonschema:"description=HTTP headers for HTTP/SSE MCP servers"`
@@ -221,7 +222,7 @@ type Options struct {
 	DebugLSP                  bool         `json:"debug_lsp,omitempty" jsonschema:"description=Enable debug logging for LSP servers,default=false"`
 	DisableAutoSummarize      bool         `json:"disable_auto_summarize,omitempty" jsonschema:"description=Disable automatic conversation summarization,default=false"`
 	DataDirectory             string       `json:"data_directory,omitempty" jsonschema:"description=Directory for storing application data (relative to working directory),default=.crush,example=.crush"` // Relative to the cwd
-	DisabledTools             []string     `json:"disabled_tools" jsonschema:"description=Tools to disable"`
+	DisabledTools             []string     `json:"disabled_tools,omitempty" jsonschema:"description=List of built-in tools to disable and hide from the agent,example=bash,example=sourcegraph"`
 	DisableProviderAutoUpdate bool         `json:"disable_provider_auto_update,omitempty" jsonschema:"description=Disable providers auto-update,default=false"`
 	Attribution               *Attribution `json:"attribution,omitempty" jsonschema:"description=Attribution settings for generated content"`
 	DisableMetrics            bool         `json:"disable_metrics,omitempty" jsonschema:"description=Disable sending metrics,default=false"`

schema.json

@@ -229,6 +229,16 @@
           "description": "Whether this MCP server is disabled",
           "default": false
         },
+        "disabled_tools": {
+          "items": {
+            "type": "string",
+            "examples": [
+              "get-library-doc"
+            ]
+          },
+          "type": "array",
+          "description": "List of tools from this MCP server to disable"
+        },
         "timeout": {
           "type": "integer",
           "description": "Timeout in seconds for MCP server connections",
@@ -386,10 +396,14 @@
         },
         "disabled_tools": {
           "items": {
-            "type": "string"
+            "type": "string",
+            "examples": [
+              "bash",
+              "sourcegraph"
+            ]
           },
           "type": "array",
-          "description": "Tools to disable"
+          "description": "List of built-in tools to disable and hide from the agent"
         },
         "disable_provider_auto_update": {
           "type": "boolean",
@@ -418,10 +432,7 @@
         }
       },
       "additionalProperties": false,
-      "type": "object",
-      "required": [
-        "disabled_tools"
-      ]
+      "type": "object"
     },
     "Permissions": {
       "properties": {