diff --git a/src/run.js b/src/run.js
index f1c3bf5..6dd02c8 100644
--- a/src/run.js
+++ b/src/run.js
@@ -45,6 +45,25 @@ function makeExecutor(bundle) {
   };
 }
 
+/**
+ * Build a name -> rendered-arguments function for the bundle, used to log
+ * each call. Tools that do not provide a `render` fall back to a plain
+ * JSON rendering of the arguments.
+ */
+function makeRenderer(bundle) {
+  const byName = new Map(bundle.map((tool) => [tool.name, tool]));
+
+  return function render(name, args) {
+    const tool = byName.get(name);
+    if (!tool || typeof tool.render !== 'function') return JSON.stringify(args || {});
+    try {
+      return tool.render(args || {});
+    } catch (err) {
+      return JSON.stringify(args || {});
+    }
+  };
+}
+
 /* ------------------------------------------------------------------ *
  * Tool-call extraction
  * ------------------------------------------------------------------ */
@@ -142,6 +161,7 @@ async function run({
     parameters,
   }));
   const execute = makeExecutor(bundle);
+  const render = makeRenderer(bundle);
 
   const history = Array.isArray(messages) ? messages.slice() : [];
 
@@ -188,10 +208,7 @@ async function run({
         role: 'tool',
         content: call,
       });
-    }
-
-    if (calls.length) {
-      console.log('called: ' + calls.map(c => c.tool_name));
+      process.stderr.write(`called: ${call.tool_name} ${render(call.tool_name, call.arguments)}\n`);
     }
 
     if (verify && verify()) {
diff --git a/src/tools.js b/src/tools.js
index 8957709..44feb59 100644
--- a/src/tools.js
+++ b/src/tools.js
@@ -149,6 +149,19 @@ function applyEdit(content, { search, replace = '', regex, global }) {
   return content.slice(0, at) + replace + content.slice(at + search.length);
 }
 
+/** Collapse whitespace and clip to `max` characters for single-line output. */
+function oneLine(value, max = 60) {
+  const text = String(value ?? '').replace(/\s+/g, ' ').trim();
+  return text.length > max ? `${text.slice(0, max - 1)}\u2026` : text;
+}
+
+/** Fallback argument rendering: values joined, JSON for non-strings. */
+function defaultRender(args) {
+  return Object.values(args ?? {})
+    .map((value) => (typeof value === 'string' ? value : JSON.stringify(value)))
+    .join(' ');
+}
+
 /* ------------------------------------------------------------------ *
  * Tool base class
  * ------------------------------------------------------------------ */
@@ -181,6 +194,16 @@ export class Tool {
     return this.run(args ?? {});
   }
 
+  /**
+   * One-line rendering of a call's arguments, used when logging the call.
+   * Subclasses override this when a more legible summary is possible.
+   */
+  render(args) {
+    // returning all json for all calls bloats
+    return '';
+    //return defaultRender(args);
+  }
+
   /** Resolve `file` against the root, asserting the given permission. */
   resolve(file, verb) {
     const abs = path.resolve(this.root, file);
@@ -206,6 +229,11 @@ class ReadFile extends Tool {
     required: ['path'],
   };
 
+  render({ path: file, lineStart, lineEnd }) {
+    const range = lineStart || lineEnd ? `:${lineStart ?? 1}-${lineEnd ?? 'eof'}` : '';
+    return `${file}${range}`;
+  }
+
   run({ path: file, lineStart, lineEnd }) {
     const abs = this.resolve(file, 'read');
 
@@ -236,6 +264,10 @@ class ListDir extends Tool {
     required: [],
   };
 
+  render({ path: dir }) {
+    return dir || '.';
+  }
+
   run({ path: dir }) {
     const abs = this.resolve(dir || '.', 'read');
 
@@ -263,6 +295,10 @@ class FindFiles extends Tool {
     required: ['pattern'],
   };
 
+  render({ pattern, path: dir }) {
+    return dir ? `${pattern} in ${dir}` : pattern;
+  }
+
   run({ pattern, path: dir = '.', limit = 200 }) {
     const abs = this.resolve(dir, 'read');
     const match = globToRegExp(pattern);
@@ -307,6 +343,10 @@ class SearchFiles extends Tool {
     required: ['pattern'],
   };
 
+  render({ pattern, path: dir = '.', glob = '**/*' }) {
+    return `${pattern} in ${dir} (${glob})`;
+  }
+
   run({
     pattern,
     path: dir = '.',
@@ -390,6 +430,10 @@ class WriteFile extends Tool {
     required: ['path', 'content'],
   };
 
+  render({ path: file }) {
+    return file;
+  }
+
   run({ path: file, content }) {
     const abs = this.resolve(file, 'write');
     fs.mkdirSync(path.dirname(abs), { recursive: true });
@@ -415,6 +459,10 @@ class UpdateFile extends Tool {
     required: ['path', 'search'],
   };
 
+  render({ path: file, search }) {
+    return `${file}: ${oneLine(search)}`;
+  }
+
   run({ path: file, search, replace = '', global, regex }) {
     const abs = this.resolve(file, 'write');
     const content = fs.readFileSync(abs, 'utf8');
@@ -450,6 +498,10 @@ class MultiEdit extends Tool {
     required: ['path', 'edits'],
   };
 
+  render({ path: file, edits }) {
+    return `${file} (${Array.isArray(edits) ? edits.length : 0} edits)`;
+  }
+
   run({ path: file, edits }) {
     const abs = this.resolve(file, 'write');
     const original = fs.readFileSync(abs, 'utf8');
@@ -504,12 +556,13 @@ function selectDefaults(selection) {
  * to the resolved scope so it only receives the call arguments.
  */
 function wrap(tool, root) {
-  const { name, description, parameters, scope, handler } = tool;
+  const { name, description, parameters, scope, handler, render } = tool;
   return {
     name,
     description,
     parameters,
     handler: (args) => handler(args ?? {}, { root, scope }),
+    render: typeof render === 'function' ? render : defaultRender,
   };
 }