llmcapa

Lookup capabilities (context window, modalities, supported features) of various LLM models — fully offline by default.

Features

• Comprehensive Bundled Data: Offline capability data for OpenAI, Anthropic, Google (Gemini), Microsoft (Phi), Amazon (Nova/Titan), Meta (Llama), Mistral, Qwen, DeepSeek, NVIDIA, and Japanese domestic models (NTT tsuzumi, PFN PLaMo, ELYZA, etc. adopted by the Digital Agency's "GENNAI" platform).
• Zero Runtime Dependencies: Built entirely on the Python standard library.
• Alias Resolution: Automatically resolves aliases and provider-specific names (e.g., gpt-4o-2024-08-06 -> gpt-4o, gemini-1.5-pro-preview-0409 -> gemini-1.5-pro).
• Advanced Feature Queries: Check support for vision, multimodal, chat_completion, responses_api, reasoning_effort, thinking_budget, and specific input/output modalities (e.g., image_input, image_output, audio_input).
• High Performance: Evaluated feature checks are cached internally using memoization to avoid redundant calculations.
• Cost Estimation: Estimate API costs based on input and output token counts.
• Drop-in Replacement Checker: Check if a model can be safely replaced by another model based on context window and required features.
• Tokenizer Mapping: Access tokenizer names (e.g., o200k_base) directly from model capabilities.
• Extendable: Load your own local JSON model definitions.
• CLI Included: Query and list model capabilities directly from your terminal.

Install

pip install llmcapa

Or from source:

pip install .

Usage

Basic Lookup

import llmcapa

# Get model capabilities (case-insensitive, alias-resolved)
cap = llmcapa.get("gpt-4o")
print(cap.context_window)       # 128000
print(cap.max_output_tokens)    # 16384
print(cap.tokenizer_name)       # "o200k_base"

# Check feature support (using strings or Feature enum)
from llmcapa import Feature, ReasoningEffort

print(cap.supports(Feature.LLMC_FEAT_VISION))             # True
print(cap.supports(Feature.LLMC_FEAT_RESPONSES_API))      # True
print(cap.supports(Feature.LLMC_FEAT_REASONING_EFFORT))   # False

# Use ReasoningEffort enum for models supporting reasoning_effort
print(ReasoningEffort.LLMC_EFFORT_HIGH)                   # "high"
# List all supported features
print(cap.features())
# ['chat_completion', 'function_calling', 'image', 'image_input', 'image_output', 'json_mode', 'multimodal', 'responses_api', 'streaming', 'text', 'text_input', 'text_output', 'vision']

Token & Cost Estimation

Roughly estimate the number of tokens for a given text (supporting 30+ major languages) and calculate API costs:

Note

Token estimation is a lightweight, offline approximation. For exact token counts, please use the official APIs or dedicated tokenizers from each provider.

gpt = llmcapa.get("gpt-4o")

# Estimate tokens for multilingual text
# If `tiktoken` is installed, it dynamically uses it for exact OpenAI token counts.
# Otherwise, it falls back to a highly-optimized, standard-library-only estimation.
text = "Hello world! こんにちは世界。"
tokens = gpt.estimate_tokens(text)
print(tokens)  # 10 (estimated tokens)

# Estimate API costs based on token counts (returns cost and currency)
res = gpt.estimate_cost(input_tokens=1500, output_tokens=500)
print(res)  # {'cost': 0.00875, 'currency': 'USD'}

Drop-in Replacement Checker

Check if a model can be safely replaced by another model. The replacement model must have a context window at least as large as the target model and support all required features.

gpt4o = llmcapa.get("gpt-4o")
gpt4o_mini = llmcapa.get("gpt-4o-mini")
gemini = llmcapa.get("gemini-3.5-flash")

# gpt-4o-mini has the same context window but lacks image_output (which gpt-4o supports)
print(gpt4o.can_be_replaced_by(gpt4o_mini))  # False

# gemini-3.5-flash has a larger context window but also lacks image_output
print(gpt4o.can_be_replaced_by(gemini))  # False

# If we only require vision and function_calling, gemini-3.5-flash can replace gpt-4o
print(gpt4o.can_be_replaced_by(gemini, required_features=["vision", "function_calling"]))  # True

Modality & Multimodal Checks

You can check specific input/output modalities or general multimodal support using Feature enum:

from llmcapa import Feature

gemini = llmcapa.get("gemini-3.5-flash")

print(gemini.supports(Feature.LLMC_FEAT_MULTIMODAL))    # True (supports multiple modalities)
print(gemini.supports(Feature.LLMC_FEAT_AUDIO_INPUT))   # True
print(gemini.supports(Feature.LLMC_FEAT_IMAGE_OUTPUT))  # False

Reasoning & Thinking Checks

Differentiate between OpenAI-style reasoning_effort and Anthropic-style thinking_budget using Feature enum:

from llmcapa import Feature

o1 = llmcapa.get("o1")
print(o1.supports(Feature.LLMC_FEAT_REASONING_EFFORT))  # True
print(o1.supports(Feature.LLMC_FEAT_THINKING_BUDGET))   # False

claude = llmcapa.get("claude-3-7-sonnet")
print(claude.supports(Feature.LLMC_FEAT_REASONING_EFFORT))  # False
print(claude.supports(Feature.LLMC_FEAT_THINKING_BUDGET))   # True

Listing & Searching Models

# List all models for a specific provider
for c in llmcapa.list_models(provider="anthropic"):
    print(c.model_id, c.context_window)

# Search models by capability criteria
big_reasoning_models = llmcapa.find(
    supports_reasoning=True,
    min_context_window=200000
)

On-demand OpenRouter Integration (Caching)

To update model data or fetch the latest pricing, you can optionally fetch and register models from the OpenRouter API on-demand using fetch_openrouter(). The response is cached locally in ~/.llmcapa/openrouter_cache.json and automatically loaded on subsequent imports, keeping the library fully offline during regular usage.

# Fetch and register OpenRouter models dynamically
count = llmcapa.fetch_openrouter()
print(f"Registered {count} models from OpenRouter!")

# Lookup using OpenRouter model ID
cap = llmcapa.get("meta-llama/llama-3.3-70b-instruct")
print(cap.context_window)  # 131072
print(cap.pricing)         # {'input_per_1m': 0.1, 'output_per_1m': 0.32, 'currency': 'USD'}

Custom Local Data

Load your own model definitions from a local JSON file:

llmcapa.load_extra("my_models.json")

my_models.json format:

{
  "models": [
    {
      "provider": "local",
      "model_id": "my-custom-model",
      "context_window": 32768,
      "max_output_tokens": 4096,
      "supports_function_calling": true,
      "aliases": ["my-model-latest"]
    }
  ]
}

Development

For details on how to extend the library, add new providers, or implement new feature flags, please refer to the DEVELOP.md guide.

CLI

# Show capabilities of a specific model
llmcapa show gpt-4o
llmcapa show gpt-4o --json

# List all known models
llmcapa list
llmcapa list --provider google
llmcapa list --json --no-deprecated

# List all known providers
llmcapa providers

# Explicitly fetch and update the OpenRouter models cache (forces cache refresh)
llmcapa update

Notes

• Static Snapshot: Bundled capability data is a static snapshot. While we strive to keep it updated with the latest models (including GPT-5.5, Claude Fable, Gemini 3.5, DeepSeek V4, etc.), providers change limits and pricing frequently. Use fetch_openrouter() or verify with official documentation when absolute accuracy is critical.

License

Apache License 2.0