diff --git a/src/cli/cli.c b/src/cli/cli.c
index c20b9b584..645331f19 100644
--- a/src/cli/cli.c
+++ b/src/cli/cli.c
@@ -5346,17 +5346,28 @@ bool cbm_config_get_bool(cbm_config_t *cfg, const char *key, bool default_val) {
     return default_val;
 }
 
-int cbm_config_get_int(cbm_config_t *cfg, const char *key, int default_val) {
-    const char *val = cbm_config_get(cfg, key, NULL);
-    if (!val) {
-        return default_val;
+static bool cbm_config_parse_decimal_int(const char *value, int *out) {
+    if (!value || !out) {
+        return false;
     }
     char *endptr;
-    long v = strtol(val, &endptr, CLI_STRTOL_BASE);
-    if (endptr == val || *endptr != '\0') {
+    errno = 0;
+    long parsed = strtol(value, &endptr, CLI_STRTOL_BASE);
+    if (errno == ERANGE || endptr == value || *endptr != '\0' ||
+        parsed < INT_MIN || parsed > INT_MAX) {
+        return false;
+    }
+    *out = (int)parsed;
+    return true;
+}
+
+int cbm_config_get_int(cbm_config_t *cfg, const char *key, int default_val) {
+    const char *val = cbm_config_get(cfg, key, NULL);
+    int parsed = 0;
+    if (!cbm_config_parse_decimal_int(val, &parsed)) {
         return default_val;
     }
-    return (int)v;
+    return parsed;
 }
 
 static bool cbm_config_value_matches_enum(const char *range, const char *value) {
@@ -5378,7 +5389,19 @@ static bool cbm_config_value_matches_enum(const char *range, const char *value)
     return false;
 }
 
+static bool cbm_config_decimal_integer_in_range(const char *value, long minimum, long maximum) {
+    int parsed = 0;
+    if (!cbm_config_parse_decimal_int(value, &parsed)) {
+        return false;
+    }
+    return parsed >= minimum && parsed <= maximum;
+}
+
 static bool cbm_config_value_is_valid(const char *key, const char *value) {
+    if (key && strcmp(key, CBM_CONFIG_AUTO_DEP_LIMIT) == 0 &&
+        !cbm_config_decimal_integer_in_range(value, 0, CBM_MAX_AUTO_DEP_LIMIT)) {
+        return false;
+    }
     for (size_t i = 0; CBM_CONFIG_REGISTRY[i].key; i++) {
         if (strcmp(CBM_CONFIG_REGISTRY[i].key, key) == 0) {
             return cbm_config_value_matches_enum(CBM_CONFIG_REGISTRY[i].range, value);
@@ -10538,7 +10561,7 @@ const cbm_config_entry_t CBM_CONFIG_REGISTRY[] = {
      "future automatic dependency indexing; it does not delete dependency projects already indexed."},
     {CBM_CONFIG_AUTO_DEP_LIMIT, CBM_STRINGIFY(CBM_DEFAULT_AUTO_DEP_LIMIT), NULL, "Dependencies",
      "Max number of packages to auto-index",
-     "0-10000",
+     "0-" CBM_STRINGIFY(CBM_MAX_AUTO_DEP_LIMIT),
      "When more packages are installed than this limit, the most-imported packages are selected "
      "(ranked by project import references, ties broken by name). Raise to 100+ for comprehensive "
      "dependency analysis. 0 = unlimited (may be very slow for large dependency trees)."},
@@ -10590,12 +10613,11 @@ int cbm_config_get_effective_int(cbm_config_t *cfg, const char *key, int default
     if (!val || !val[0]) {
         return default_val;
     }
-    char *endptr;
-    long parsed = strtol(val, &endptr, CLI_STRTOL_BASE);
-    if (endptr == val || *endptr != '\0') {
+    int parsed = 0;
+    if (!cbm_config_parse_decimal_int(val, &parsed)) {
         return default_val;
     }
-    return (int)parsed;
+    return parsed;
 }
 
 /* ── Config CLI subcommand ────────────────────────────────────── */
diff --git a/src/depindex/depindex.c b/src/depindex/depindex.c
index d73e09a8f..a39b44795 100644
--- a/src/depindex/depindex.c
+++ b/src/depindex/depindex.c
@@ -739,19 +739,27 @@ int cbm_discover_installed_deps(cbm_pkg_manager_t mgr, const char *project_root,
 
 /* ── Auto-Index ────────────────────────────────────────────────── */
 
+int cbm_dep_normalize_configured_limit(int limit, int default_limit) {
+    if (limit == 0) {
+        return -1;
+    }
+    if (limit > 0 && limit <= CBM_MAX_AUTO_DEP_LIMIT) {
+        return limit;
+    }
+    return default_limit > 0 && default_limit <= CBM_MAX_AUTO_DEP_LIMIT
+               ? default_limit
+               : CBM_DEFAULT_AUTO_DEP_LIMIT;
+}
+
 int cbm_dep_auto_index_effective_limit(cbm_config_t *cfg, int default_limit) {
-    if (!cbm_config_get_bool(cfg, CBM_CONFIG_AUTO_INDEX_DEPS,
-                             CBM_DEFAULT_AUTO_INDEX_DEPS)) {
+    if (!cbm_config_get_bool(cfg, CBM_CONFIG_AUTO_INDEX_DEPS, CBM_DEFAULT_AUTO_INDEX_DEPS)) {
         return 0;
     }
 
     int limit = cbm_config_get_int(cfg, CBM_CONFIG_AUTO_DEP_LIMIT, default_limit);
     /* The direct API keeps max_deps=0 as disabled. The config registry documents
      * auto_dep_limit=0 as unlimited, so map configured callers to -1 here. */
-    if (limit <= 0) {
-        return -1;
-    }
-    return limit;
+    return cbm_dep_normalize_configured_limit(limit, default_limit);
 }
 
 /* Auto-detect ecosystem, discover deps, index each via flush_to_store.
diff --git a/src/depindex/depindex.h b/src/depindex/depindex.h
index f37e4975c..39df0a6b7 100644
--- a/src/depindex/depindex.h
+++ b/src/depindex/depindex.h
@@ -48,6 +48,7 @@ static const char *CBM_MANIFEST_FILES[] = {
 #define CBM_DEFAULT_AUTO_INDEX_DEPS false
 #define CBM_DEFAULT_AUTO_INDEX_DEPS_STR "false"
 #define CBM_DEFAULT_AUTO_DEP_LIMIT 20
+#define CBM_MAX_AUTO_DEP_LIMIT 10000
 #define CBM_DEFAULT_DEP_MAX_FILES 1000
 
 /* Config key strings */
@@ -163,4 +164,8 @@ int cbm_dep_link_cross_edges(cbm_store_t *store, const char *project_name);
  * Return 0 to disable, -1 for unlimited, or a positive package count. */
 int cbm_dep_auto_index_effective_limit(cbm_config_t *cfg, int default_limit);
 
+/* Normalize an enabled auto_dep_limit value: 0 is unlimited, valid positive
+ * values are retained, and out-of-range values fall back to a bounded default. */
+int cbm_dep_normalize_configured_limit(int limit, int default_limit);
+
 #endif /* CBM_DEPINDEX_H */
diff --git a/src/mcp/mcp.c b/src/mcp/mcp.c
index b794103b4..cb012398e 100644
--- a/src/mcp/mcp.c
+++ b/src/mcp/mcp.c
@@ -1052,8 +1052,10 @@ static const tool_def_t TOOLS[] = {
      "Use [\\\"*\\\"] for all indexed projects. Run list_projects to see available projects.\"},"
      "\"auto_index_deps\":{\"type\":\"boolean\",\"description\":"
      "\"Set false to skip dependency package indexing for this call. Default follows config auto_index_deps.\"},"
-     "\"auto_dep_limit\":{\"type\":\"integer\",\"description\":"
-     "\"Dependency package cap for this call. Default follows config auto_dep_limit; 0 means unlimited.\"},"
+     "\"auto_dep_limit\":{\"type\":\"integer\",\"minimum\":0,\"maximum\":"
+     CBM_STRINGIFY(CBM_MAX_AUTO_DEP_LIMIT) ",\"description\":"
+     "\"Dependency package cap for this call from 1 to " CBM_STRINGIFY(CBM_MAX_AUTO_DEP_LIMIT)
+     ". Default follows config auto_dep_limit; 0 means unlimited.\"},"
      "\"name\":{\"type\":\"string\",\"description\":"
      "\"Override the derived project name. Non-ASCII bytes are encoded and unsafe path characters "
      "are normalized.\"},"
@@ -2572,7 +2574,7 @@ static int cbm_mcp_effective_auto_dep_limit(cbm_mcp_server_t *srv, const char *a
     if (cbm_mcp_has_arg(args_json, CBM_CONFIG_AUTO_DEP_LIMIT)) {
         limit = cbm_mcp_get_int_arg(args_json, CBM_CONFIG_AUTO_DEP_LIMIT, limit);
     }
-    return limit <= 0 ? -1 : limit;
+    return cbm_dep_normalize_configured_limit(limit, CBM_DEFAULT_AUTO_DEP_LIMIT);
 }
 
 /* Query routes deliberately cache read-only stores. Mutation routes must never
diff --git a/tests/test_cli.c b/tests/test_cli.c
index b98ab83b5..96d0e10d6 100644
--- a/tests/test_cli.c
+++ b/tests/test_cli.c
@@ -6879,6 +6879,10 @@ TEST(cli_config_get_int) {
     cbm_config_set(cfg, "limit", "abc");
     ASSERT_EQ(cbm_config_get_int(cfg, "limit", 50000), 50000);
 
+    /* Values outside int range must not wrap into a valid limit. */
+    cbm_config_set(cfg, "limit", "999999999999999999999999");
+    ASSERT_EQ(cbm_config_get_int(cfg, "limit", 50000), 50000);
+
     cbm_config_close(cfg);
     test_rmdir_r(tmpdir);
     PASS();
@@ -6962,6 +6966,9 @@ TEST(cli_config_registry_auto_dep_limit_uses_shared_default) {
 
     ASSERT_NOT_NULL(found);
     ASSERT_EQ(atoi(found->default_val), CBM_DEFAULT_AUTO_DEP_LIMIT);
+    char expected_range[CBM_SZ_32];
+    snprintf(expected_range, sizeof(expected_range), "0-%d", CBM_MAX_AUTO_DEP_LIMIT);
+    ASSERT_STR_EQ(found->range, expected_range);
     PASS();
 }
 
diff --git a/tests/test_depindex.c b/tests/test_depindex.c
index 8c44e1f9a..f3d91eb56 100644
--- a/tests/test_depindex.c
+++ b/tests/test_depindex.c
@@ -1090,6 +1090,18 @@ TEST(test_auto_index_deps_config_limit_policy) {
     ASSERT_EQ(cbm_dep_auto_index_effective_limit(cfg, CBM_DEFAULT_AUTO_DEP_LIMIT), 7);
     ASSERT_EQ(cbm_config_set(cfg, CBM_CONFIG_AUTO_DEP_LIMIT, "0"), 0);
     ASSERT_EQ(cbm_dep_auto_index_effective_limit(cfg, CBM_DEFAULT_AUTO_DEP_LIMIT), -1);
+    ASSERT_EQ(
+        cbm_dep_normalize_configured_limit(CBM_MAX_AUTO_DEP_LIMIT, CBM_DEFAULT_AUTO_DEP_LIMIT),
+        CBM_MAX_AUTO_DEP_LIMIT);
+    ASSERT_EQ(cbm_dep_normalize_configured_limit(-1, CBM_DEFAULT_AUTO_DEP_LIMIT),
+              CBM_DEFAULT_AUTO_DEP_LIMIT);
+    ASSERT_EQ(
+        cbm_dep_normalize_configured_limit(CBM_MAX_AUTO_DEP_LIMIT + 1, CBM_MAX_AUTO_DEP_LIMIT + 1),
+        CBM_DEFAULT_AUTO_DEP_LIMIT);
+    ASSERT_NEQ(cbm_config_set(cfg, CBM_CONFIG_AUTO_DEP_LIMIT, "-1"), 0);
+    char over_limit[CBM_SZ_32];
+    snprintf(over_limit, sizeof(over_limit), "%d", CBM_MAX_AUTO_DEP_LIMIT + 1);
+    ASSERT_NEQ(cbm_config_set(cfg, CBM_CONFIG_AUTO_DEP_LIMIT, over_limit), 0);
 
     cbm_config_close(cfg);
     cleanup_fixture_dir(cache_tmp);
diff --git a/tests/test_mcp.c b/tests/test_mcp.c
index f2bdba876..421b4c0d8 100644
--- a/tests/test_mcp.c
+++ b/tests/test_mcp.c
@@ -610,6 +610,21 @@ TEST(mcp_canonical_input_schemas_cover_implemented_format_and_verbose_options) {
     PASS();
 }
 
+TEST(mcp_index_repository_auto_dep_limit_schema_uses_shared_bounds) {
+    const char *schema_json = cbm_mcp_tool_input_schema("index_repository");
+    ASSERT_NOT_NULL(schema_json);
+    yyjson_doc *doc = yyjson_read(schema_json, strlen(schema_json), 0);
+    ASSERT_NOT_NULL(doc);
+    yyjson_val *properties = yyjson_obj_get(yyjson_doc_get_root(doc), "properties");
+    ASSERT_TRUE(yyjson_is_obj(properties));
+    yyjson_val *limit = yyjson_obj_get(properties, CBM_CONFIG_AUTO_DEP_LIMIT);
+    ASSERT_TRUE(yyjson_is_obj(limit));
+    ASSERT_EQ(yyjson_get_int(yyjson_obj_get(limit, "minimum")), 0);
+    ASSERT_EQ(yyjson_get_int(yyjson_obj_get(limit, "maximum")), CBM_MAX_AUTO_DEP_LIMIT);
+    yyjson_doc_free(doc);
+    PASS();
+}
+
 TEST(mcp_tools_have_behavior_annotations) {
     struct {
         const char *name;
@@ -12726,6 +12741,7 @@ SUITE(mcp) {
     RUN_TEST(mcp_tools_list_latest_metadata);
     RUN_TEST(mcp_tool_input_schemas_are_closed_in_classic_and_streamlined_modes);
     RUN_TEST(mcp_canonical_input_schemas_cover_implemented_format_and_verbose_options);
+    RUN_TEST(mcp_index_repository_auto_dep_limit_schema_uses_shared_bounds);
     RUN_TEST(mcp_tools_have_behavior_annotations);
     RUN_TEST(mcp_index_repository_declares_name_override_issue571);
     RUN_TEST(mcp_tools_array_schemas_have_items);