delta-exchange-mcp: Instructions file for Claude Code

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project in one line

FastMCP server (stdio only) that wraps Delta Exchange India's REST API as MCP tools — public market data unconditionally, authenticated read-only account tools when DELTA_API_KEY/DELTA_API_SECRET are set, plus authenticated trading mutations when DELTA_MCP_MODE=trade is also set.

Style

Don't add typing slop. In particular:

• Don't annotate pytest fixtures (tmp_path, monkeypatch, etc.) — pytest discovers them by name, the annotation adds nothing.
• Don't write **kwargs: Any / -> Any on internal test helpers. If the only honest type is Any, leave it off.
• Use Any only when it carries real information: a public boundary that genuinely accepts arbitrary JSON, a return type that is genuinely heterogeneous. Otherwise prefer the real type or no annotation at all.
• Don't add from typing import Any just to satisfy a redundant annotation.

Commands

uv sync                                        # install deps (runtime + dev)
uv run pytest                                  # run full suite (asyncio_mode=auto)
uv run pytest tests/test_market_tools.py::test_429_retries_then_succeeds  # single test
uv run ruff check src tests scripts            # lint
uv run ruff check --fix src tests scripts      # lint + autofix

uv run delta-exchange-mcp                      # stdio (the only transport)

uv run python scripts/smoke.py                 # live smoke against DELTA_MCP_ENV

bash scripts/inspect.sh --cli --method tools/list
bash scripts/inspect.sh --cli --method tools/call --tool-name get_ticker --tool-arg symbol=BTCUSD
bash scripts/inspect.sh                                                          # Inspector web UI on :6274

Rebuilding the editable install after changing pyproject.toml or entry points: uv sync again — uv run caches the build.

Architecture

Tool registration pattern