graph-tool-call MCP server

graph-tool-call

Graph-structured retrieval for large LLM tool catalogs.

Find the target tool, the prerequisite tools that produce its inputs, and the smallest schema bundle that fits the planner's token budget.

Documentation · Quickstart · PyPI · Benchmarks

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The Problem

A semantic search for "refund an order" can find refundOrder. That is not enough when the operation requires an order_id that the user does not have. A usable candidate set also needs the operation that produces that field:

findOrdersByEmail(email) -> order_id -> refundOrder(order_id)

Large catalogs create a second problem: sending every schema to the model wastes context and can lower selection quality. graph-tool-call treats retrieval as a contract-aware graph problem instead of flat similarity search.

It provides:

• deterministic ingestion from OpenAPI, GraphQL introspection, MCP tools, Python functions, and structured tool catalogs;
• hybrid target retrieval with keyword, graph, optional embedding, and MCP annotation signals;
• evidence-backed target selection and typed prerequisite expansion;
• token-budgeted, contract-projected schemas for the model-facing catalog;
• readiness, failure, and trace metadata for application-side diagnostics;
• adapters for OpenAI, Anthropic, LangChain v1, MCP, Docker, and Kubernetes.

Authentication, tenant policy, approval, and product-specific execution remain in the host application.

See It in 30 Seconds

No model, API key, or network call is required:

uvx graph-tool-call demo dependency-chain

Selected target:
  refundOrder(order_id)

Required producer:
  findOrdersByEmail(email) -> order_id
  evidence: api_contract, openapi_link

Execution order:
  1. findOrdersByEmail
  2. refundOrder

Planner context:
  6 catalog tools -> 2 required tools
  estimated tokens: 1476 -> 160 (89% fewer)

This demo runs the real retriever, deterministic target selector, typed dependency closure, and schema admission pipeline.

Installation

The core search and graph package uses only the Python standard library. Optional integrations are installed explicitly:

pip install graph-tool-call
pip install "graph-tool-call[openapi]"       # YAML OpenAPI documents
pip install "graph-tool-call[korean]"        # Kiwi tokenizer
pip install "graph-tool-call[langchain]"     # LangChain v1 middleware
pip install "graph-tool-call[mcp]"           # MCP server and proxy
pip install "graph-tool-call[all]"           # all optional features

Python 3.10 through 3.14 are tested in CI.

Build and Search

OpenAPI

from graph_tool_call import ToolGraph

graph = ToolGraph.from_url(
    "https://petstore3.swagger.io/api/v3/openapi.json",
    cache="petstore.graph.json",
)

for result in graph.retrieve_with_scores("create a new pet", top_k=5):
    print(result.tool.name, result.score, result.confidence)

OpenAPI ingestion preserves request and response schemas, parameter locations, content types, security requirements, links, examples, response envelopes, and typed consumes/produces contracts. Swagger 2.0, OpenAPI 3.0, and OpenAPI 3.1 are supported.

Inspect a collection before exposing it to an agent:

graph-tool-call inspect-openapi ./openapi.json --json
graph-tool-call build-openapi-collection ./openapi.json -o collection.json

The report contains stable readiness issue codes, semantic coverage, and edge quality rather than a single opaque score.

Other sources

from graph_tool_call.ingest import ingest_source

openapi_result = ingest_source(openapi_document)
graphql_result = ingest_source(introspection_result)
mcp_result = ingest_source({"tools": mcp_tools}, format_hint="mcp-tools")
python_result = ingest_source([read_file, write_file])

Every adapter returns normalized ToolSchema objects, capability metadata, and structured unsupported-feature diagnostics.

Choose an Integration

Environment	Recommended surface	What graph-tool-call owns
Python application	ToolGraph / graphify APIs	ingest, search, evidence, dependency closure
OpenAI Responses or Chat Completions	patch_openai	per-request function-tool filtering
Anthropic Messages	patch_anthropic	per-request tool filtering
LangChain v1	create_tool_selection_middleware	model-call tool selection
Claude Code, Cursor, Windsurf	MCP proxy	many MCP backends behind 3 gateway tools
OpenAI Agents, PydanticAI, Google ADK	remote MCP server	protocol-neutral search service
Docker or Kubernetes	Streamable HTTP MCP	private deployable service

See the compatibility matrix for validation boundaries. Protocol compatibility does not imply that every framework or cloud release is tested by this repository.

OpenAI Responses

from graph_tool_call.middleware import patch_openai

patch_openai(client, graph=graph, top_k=5)

response = client.responses.create(
    model=model_name,
    input="delete a user account",
    tools=all_function_tools,
)

Hosted tools such as web search pass through unchanged. The same patch keeps legacy Chat Completions support.

LangChain v1

from langchain.agents import create_agent
from graph_tool_call.langchain import create_tool_selection_middleware

selection = create_tool_selection_middleware(langchain_tools, top_k=5)
agent = create_agent(
    model,
    tools=langchain_tools,
    middleware=[selection],
)

The middleware intersects with tools still allowed by earlier permission or feature-flag middleware; it does not reintroduce filtered tools.

MCP server

graph-tool-call ingest ./openapi.json -o graph.json
graph-tool-call serve \
  --graph graph.json \
  --transport streamable-http \
  --host 127.0.0.1 \
  --port 8000

The MCP endpoint is /mcp; HTTP deployments also expose /healthz and /readyz. Keep remote endpoints private or behind an authenticated gateway.

MCP proxy

graph-tool-call proxy \
  --config ./mcp-backends.json \
  --transport streamable-http

The proxy accepts local stdio, SSE, and Streamable HTTP backends. In gateway mode it exposes search_tools, get_tool_schema, and call_backend_tool, then notifies capable clients when matching backend tools become visible.

Reproducible Evidence

The release headline is deliberately model-free and small enough to replay in CI. On seven curated commerce cases, adding typed producer expansion to the same selected target produced:

Metric	Target only	Target + graph producers
Required-producer recall	14.3%	100%
Candidate plan coverage	47.6%	100%
Candidate binding support	14.3%	100%
Target Recall@5	-	100%

The case-level v0.47.0 artifact records fixture hashes, every expected target and producer, and replay commands:

make launch-evidence
make launch-evidence-check

The separate observability artifact checks that tracing leaves engine inputs unchanged, replays deterministically, scrubs secrets, explains every decision, and stays below the documented 5ms/span p95 capture-cost gate:

make observability-evidence-check

This is an engine regression suite, not a population-level estimate of LLM tool-calling accuracy and not a state-of-the-art claim. Larger external comparisons, model-loop experiments, confidence intervals, and known weak cases are reported in Benchmark Results and the paper protocol.

Production Boundary

graph-tool-call is the retrieval and contract layer. A production adapter still owns:

• user and service authentication;
• tenant authorization and approval policy;
• downstream secrets and cookie handling;
• side-effect confirmation, cleanup, and audit retention;
• provider/model lifecycle and final response policy.

Do not store raw credentials in graph artifacts, tool descriptions, trace records, or model-visible arguments.

Documentation

Start here	Purpose
Quickstart	first search, graph, readiness, and execution loop
Mental model	understand the pipeline and boundaries
OpenAPI ingestion	contract extraction and collection build
Target selection	ranking evidence and deterministic guard
Integrations	frameworks, MCP, and deployment
API reference	stable public Python surface
Roadmap	current product and research priorities

Development

git clone https://github.com/SonAIengine/graph-tool-call.git
cd graph-tool-call
poetry install --with dev --all-extras

poetry run ruff check .
poetry run ruff format --check .
poetry run pytest tests/ -q

See CONTRIBUTING.md and the release checklist.

License

MIT