diff --git a/src/helm/benchmark/tokenizer_config_registry.py b/src/helm/benchmark/tokenizer_config_registry.py
index ab87c601c9..d2d242d150 100644
--- a/src/helm/benchmark/tokenizer_config_registry.py
+++ b/src/helm/benchmark/tokenizer_config_registry.py
@@ -26,7 +26,11 @@ class TokenizerConfig:
     tokenizer_spec: TokenizerSpec
     """Specification for instantiating the client for this tokenizer."""
 
-    # TODO: Add `end_of_text_token`` and `prefix_token``
+    end_of_text_token: Optional[str] = None
+    """The end of text token."""
+
+    prefix_token: Optional[str] = None
+    """The prefix token."""
 
 
 @dataclass(frozen=True)
diff --git a/src/helm/common/object_spec.py b/src/helm/common/object_spec.py
index 8fab448960..5669daeb33 100644
--- a/src/helm/common/object_spec.py
+++ b/src/helm/common/object_spec.py
@@ -1,6 +1,6 @@
 import importlib
 import dataclasses
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 import inspect
 from typing import Any, Callable, Dict, Optional, Tuple, Hashable, Type, TypeVar
 
@@ -13,7 +13,7 @@ class ObjectSpec:
     class_name: str
 
     # Arguments used to construct the scenario
-    args: Dict[str, Any]
+    args: Dict[str, Any] = field(default_factory=dict)
 
     def __hash__(self):
         def get_arg_value(key: str) -> Any:
diff --git a/src/helm/config/tokenizer_configs.yaml b/src/helm/config/tokenizer_configs.yaml
index 0cf211eaad..48863c1d47 100644
--- a/src/helm/config/tokenizer_configs.yaml
+++ b/src/helm/config/tokenizer_configs.yaml
@@ -1,62 +1,208 @@
 tokenizer_configs:
-  # ========== AI21 Labs ========== #
+
+  # ========== Ai21 ========== #
   - name: ai21/j1
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.ai21_tokenizer.AI21Tokenizer"
-      args: {}
-  # =============================== #
-  
-  # ========== Aleph Alpha ========== #
+    end_of_text_token: " "
+    prefix_token: ""
+  # ========================== #
+
+  # ========== AlephAlpha ========== #
   - name: AlephAlpha/luminous-base
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.aleph_alpha_tokenizer.AlephAlphaTokenizer"
-      args: {}
+    end_of_text_token: ""
+    prefix_token: ""
   - name: AlephAlpha/luminous-extended
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.aleph_alpha_tokenizer.AlephAlphaTokenizer"
-      args: {}
+    end_of_text_token: ""
+    prefix_token: ""
   - name: AlephAlpha/luminous-supreme
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.aleph_alpha_tokenizer.AlephAlphaTokenizer"
-      args: {}
+    end_of_text_token: ""
+    prefix_token: ""
   - name: AlephAlpha/luminous-world
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.aleph_alpha_tokenizer.AlephAlphaTokenizer"
-      args: {}
-  # ================================= #
-  
-  # =========== Anthropic =========== #
+    end_of_text_token: ""
+    prefix_token: ""
+  # ================================ #
+
+  # ========== Anthropic ========== #
   - name: anthropic/claude
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.anthropic_tokenizer.AnthropicTokenizer"
-      args: {}
-  # ================================= #
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  # =============================== #
+
+  # ========== Bigcode ========== #
+  - name: bigcode/santacoder
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  - name: bigcode/starcoder
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  # ============================= #
 
-  # =========== BigScience =========== #
+  # ========== Bigscience ========== #
   - name: bigscience/bloom
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
-      args: {}
+    end_of_text_token: "</s>"
+    prefix_token: "</s>"
   - name: bigscience/T0pp
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
-      args: {}
-  # ================================== #
+    end_of_text_token: "</s>"
+    prefix_token: ""
+  # ================================ #
 
-  # =========== BigCode =========== #
-  - name: bigcode/santacoder
+  # ========== Cohere ========== #
+  - name: cohere/cohere
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.cohere_tokenizer.CohereTokenizer"
+    end_of_text_token: ""
+    prefix_token: ":"
+  # ============================ #
+
+  # ========== EleutherAI ========== #
+  - name: EleutherAI/gpt-j-6B
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
-      args: {}
-  - name: bigcode/starcoder
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  - name: EleutherAI/gpt-neox-20b
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  # ================================ #
+
+  # ========== Facebook ========== #
+  - name: facebook/opt-66b
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "</s>"
+  # ============================== #
+
+  # ========== Google ========== #
+  - name: google/t5-11b
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: ""
+  - name: google/flan-t5-xxl
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: ""
+  - name: google/ul2
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: ""
+  # ============================ #
+
+  # ========== Hf-internal-testing ========== #
+  - name: hf-internal-testing/llama-tokenizer
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
+  # ========================================= #
+
+  # ========== HuggingFaceM4 ========== #
+  - name: HuggingFaceM4/idefics-9b
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
+  - name: HuggingFaceM4/idefics-9b-instruct
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
+  - name: HuggingFaceM4/idefics-80b
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
+  - name: HuggingFaceM4/idefics-80b-instruct
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
+  # =================================== #
+
+  # ========== Huggingface ========== #
+  - name: huggingface/gpt2
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  # ================================= #
+
+  # ========== Meta-llama ========== #
+  - name: meta-llama/Llama-2-7b-hf
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
+  # ================================ #
+
+  # ========== Mistralai ========== #
+  - name: mistralai/Mistral-7B-v0.1
     tokenizer_spec:
       class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
-      args: {}
+    end_of_text_token: "</s>"
+    prefix_token: "<s>"
   # =============================== #
 
-  # =========== Cohere =========== #
-  - name: cohere/cohere
+  # ========== Neurips ========== #
+  - name: neurips/local
     tokenizer_spec:
-      class_name: "helm.proxy.tokenizers.cohere_tokenizer.CohereTokenizer"
-      args: {}
-  # ============================== #
\ No newline at end of file
+      class_name: "helm.proxy.tokenizers.http_model_tokenizer.HTTPModelTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  # ============================= #
+
+  # ========== Openai ========== #
+  - name: openai/cl100k_base
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.tiktoken_tokenizer.TiktokenTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: "<|endoftext|>"
+  # ============================ #
+
+  # ========== Tiiuae ========== #
+  - name: tiiuae/falcon-7b
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.huggingface_tokenizer.HuggingFaceTokenizer"
+    end_of_text_token: "<|endoftext|>"
+    prefix_token: null
+  # ============================ #
+
+  # ========== TsinghuaKEG ========== #
+  - name: TsinghuaKEG/ice
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.ice_tokenizer.ICETokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: ""
+  # ================================= #
+
+  # ========== Yandex ========== #
+  - name: Yandex/yalm
+    tokenizer_spec:
+      class_name: "helm.proxy.tokenizers.yalm_tokenizer.YaLMTokenizer"
+    end_of_text_token: "</s>"
+    prefix_token: "</s>"
+  # ============================ #
\ No newline at end of file