3 files changed, 135 insertions, 4 deletions

diff --git a/packages/server/src/config/config.ts b/packages/server/src/config/config.ts
index 82b31902..de70144d 100644
--- a/packages/server/src/config/config.ts
+++ b/packages/server/src/config/config.ts
@@ -32,6 +32,8 @@ export class Config {
     private readonly debugMode: boolean,
     private readonly question: string | undefined, // Keep undefined possibility
     private readonly fullContext: boolean = false, // Default value here
+    private readonly toolDiscoveryCommand: string | undefined,
+    private readonly toolCallCommand: string | undefined,
   ) {
     // toolRegistry still needs initialization based on the instance
     this.toolRegistry = createToolRegistry(this);
@@ -67,6 +69,14 @@ export class Config {
   getFullContext(): boolean {
     return this.fullContext;
   }
+
+  getToolDiscoveryCommand(): string | undefined {
+    return this.toolDiscoveryCommand;
+  }
+
+  getToolCallCommand(): string | undefined {
+    return this.toolCallCommand;
+  }
 }
 
 function findEnvFile(startDir: string): string | null {
@@ -100,6 +110,8 @@ export function createServerConfig(
   debugMode: boolean,
   question: string,
   fullContext?: boolean,
+  toolDiscoveryCommand?: string,
+  toolCallCommand?: string,
 ): Config {
   return new Config(
     apiKey,
@@ -109,11 +121,13 @@ export function createServerConfig(
     debugMode,
     question,
     fullContext,
+    toolDiscoveryCommand,
+    toolCallCommand,
   );
 }
 
 function createToolRegistry(config: Config): ToolRegistry {
-  const registry = new ToolRegistry();
+  const registry = new ToolRegistry(config);
   const targetDir = config.getTargetDir();
 
   const tools: Array<BaseTool<unknown, ToolResult>> = [
@@ -137,5 +151,6 @@ function createToolRegistry(config: Config): ToolRegistry {
   for (const tool of tools) {
     registry.registerTool(tool);
   }
+  registry.discoverTools();
   return registry;
 }
diff --git a/packages/server/src/tools/shell.md b/packages/server/src/tools/shell.md
index a8a42381..66543662 100644
--- a/packages/server/src/tools/shell.md
+++ b/packages/server/src/tools/shell.md
@@ -1,6 +1,7 @@
 This tool executes a given shell command as `bash -c <command>`.
 Command can be any valid single-line Bash command.
 Command can start background processes using `&`.
+Command is executed as a subprocess.
 
 The following information is returned:
 
@@ -8,7 +9,7 @@ Command: Executed command.
 Directory: Directory (relative to project root) where command was executed, or `(root)`.
 Stdout: Output on stdout stream. Can be `(empty)` or partial on error.
 Stderr: Output on stderr stream. Can be `(empty)` or partial on error.
-Error: Error or `(none)` if no error occurred.
+Error: Error or `(none)` if no error was reported for the subprocess.
 Exit Code: Exit code or `(none)` if terminated by signal.
 Signal: Signal number or `(none)` if no signal was received.
 Background PIDs: List of background processes started or `(none)`.
diff --git a/packages/server/src/tools/tool-registry.ts b/packages/server/src/tools/tool-registry.ts
index 9ae41802..4affeca1 100644
--- a/packages/server/src/tools/tool-registry.ts
+++ b/packages/server/src/tools/tool-registry.ts
@@ -5,11 +5,94 @@
  */
 
 import { FunctionDeclaration } from '@google/genai';
-import { Tool } from './tools.js';
+import { Tool, ToolResult, BaseTool } from './tools.js';
+import { Config } from '../config/config.js';
+import { spawn, execSync } from 'node:child_process';
+
+type ToolParams = Record<string, unknown>;
+
+export class DiscoveredTool extends BaseTool<ToolParams, ToolResult> {
+  constructor(
+    private readonly config: Config,
+    readonly name: string,
+    readonly description: string,
+    readonly parameterSchema: Record<string, unknown>,
+  ) {
+    const discoveryCmd = config.getToolDiscoveryCommand()!;
+    const callCommand = config.getToolCallCommand()!;
+    description += `
+This tool was discovered from the project by executing the command \`${discoveryCmd}\` on project root.
+When called, this tool will execute the command \`${callCommand} ${name}\` on project root.
+Tool discovery and call commands can be configured in project settings.
+
+When called, the tool call command is executed as a subprocess.
+On success, tool output is returned as a json string.
+Otherwise, the following information is returned:
+
+Stdout: Output on stdout stream. Can be \`(empty)\` or partial.
+Stderr: Output on stderr stream. Can be \`(empty)\` or partial.
+Error: Error or \`(none)\` if no error was reported for the subprocess.
+Exit Code: Exit code or \`(none)\` if terminated by signal.
+Signal: Signal number or \`(none)\` if no signal was received.
+`;
+    super(name, name, description, parameterSchema);
+  }
+
+  async execute(params: ToolParams): Promise<ToolResult> {
+    const callCommand = this.config.getToolCallCommand()!;
+    const child = spawn(callCommand, [this.name]);
+    child.stdin.write(JSON.stringify(params));
+    child.stdin.end();
+    let stdout = '';
+    let stderr = '';
+    child.stdout.on('data', (data) => {
+      stdout += data.toString();
+    });
+    child.stderr.on('data', (data) => {
+      stderr += data.toString();
+    });
+    let error: Error | null = null;
+    child.on('error', (err: Error) => {
+      error = err;
+    });
+    let code: number | null = null;
+    let signal: NodeJS.Signals | null = null;
+    child.on(
+      'close',
+      (_code: number | null, _signal: NodeJS.Signals | null) => {
+        code = _code;
+        signal = _signal;
+      },
+    );
+    await new Promise((resolve) => child.on('close', resolve));
+
+    // if there is any error, non-zero exit code, signal, or stderr, return error details instead of stdout
+    if (error || code !== 0 || signal || stderr) {
+      const llmContent = [
+        `Stdout: ${stdout || '(empty)'}`,
+        `Stderr: ${stderr || '(empty)'}`,
+        `Error: ${error ?? '(none)'}`,
+        `Exit Code: ${code ?? '(none)'}`,
+        `Signal: ${signal ?? '(none)'}`,
+      ].join('\n');
+      return {
+        llmContent,
+        returnDisplay: llmContent,
+      };
+    }
+
+    return {
+      llmContent: stdout,
+      returnDisplay: stdout,
+    };
+  }
+}
 
 export class ToolRegistry {
   private tools: Map<string, Tool> = new Map();
 
+  constructor(private readonly config: Config) {}
+
   /**
    * Registers a tool definition.
    * @param tool - The tool object containing schema and execution logic.
@@ -25,8 +108,40 @@ export class ToolRegistry {
   }
 
   /**
+   * Discovers tools from project, if a discovery command is configured.
+   * Can be called multiple times to update discovered tools.
+   */
+  discoverTools(): void {
+    const discoveryCmd = this.config.getToolDiscoveryCommand();
+    if (!discoveryCmd) return;
+    // remove any previously discovered tools
+    for (const tool of this.tools.values()) {
+      if (tool instanceof DiscoveredTool) {
+        this.tools.delete(tool.name);
+      }
+    }
+    // execute discovery command and extract function declarations
+    const functions: FunctionDeclaration[] = [];
+    for (const tool of JSON.parse(execSync(discoveryCmd).toString().trim())) {
+      functions.push(...tool['function_declarations']);
+    }
+    // register each function as a tool
+    for (const func of functions) {
+      this.registerTool(
+        new DiscoveredTool(
+          this.config,
+          func.name!,
+          func.description!,
+          func.parameters! as Record<string, unknown>,
+        ),
+      );
+    }
+  }
+
+  /**
    * Retrieves the list of tool schemas (FunctionDeclaration array).
    * Extracts the declarations from the ToolListUnion structure.
+   * Includes discovered (vs registered) tools if configured.
    * @returns An array of FunctionDeclarations.
    */
   getFunctionDeclarations(): FunctionDeclaration[] {
@@ -38,7 +153,7 @@ export class ToolRegistry {
   }
 
   /**
-   * Returns an array of all registered tool instances.
+   * Returns an array of all registered and discovered tool instances.
    */
   getAllTools(): Tool[] {
     return Array.from(this.tools.values());