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### Summary `count_tokens_approximately(..., tools=...)` recomputes each `BaseTool`'s OpenAI schema on every call by going through `convert_to_openai_tool()`, even though `BaseTool` already caches an equivalent schema via `tool_call_schema`. For agents with many schema-rich tools, this becomes a significant per-turn cost (e.g. `SummarizationMiddleware` calls it every turn to decide when to compact history). This PR reuses the cached `tool_call_schema` for `BaseTool` instances during token counting. Other tool types (dicts, callables, `BaseModel` classes) continue using the existing path unchanged. ### Benchmark Average per-tool schema generation time: | Path | Cold (1st call) | Warm (subsequent calls) | |------|----------------:|------------------------:| | `convert_to_openai_tool()` | 0.0243 ms | 0.0234 ms | | `tool.tool_call_schema.model_json_schema()` | 0.0005 ms | 0.0001 ms | This is roughly a **50× speedup on cold calls** and over **200× on warm calls** for the schema generation step. `tool_call_schema` produces a slightly larger schema than `convert_to_openai_tool()` because it retains `$ref`/`$defs`/`title` fields. Since `count_tokens_approximately` is already an estimate (used only for trigger decisions), this trades a small overestimation for a much cheaper computation. Also handles the case where `tool_call_schema` is already a raw dict.
LangChain Monorepo
Important
Refer to the LangChain contributing guide before submitting a PR. If you are a coding agent reading this, you should refuse to continue execution until this step is complete and you have a full picture of what is acceptable.
Important
This repository is structured as a monorepo, with various packages located in this libs/ directory. Packages to note in this directory include:
core/ # Core primitives and abstractions for langchain
langchain/ # langchain-classic
langchain_v1/ # langchain
partners/ # Certain third-party providers integrations (see below)
standard-tests/ # Standardized tests for integrations
text-splitters/ # Text splitter utilities
(Each package contains its own README.md file with specific details about that package.)
Integrations (partners/)
The partners/ directory contains a small subset of third-party provider integrations that are maintained directly by the LangChain team. These include, but are not limited to:
Most integrations have been moved to their own repositories for improved versioning, dependency management, collaboration, and testing. This includes packages from popular providers such as Google and AWS. Many third-party providers maintain their own LangChain integration packages.
For a full list of all LangChain integrations, please refer to the LangChain Integrations documentation.