EODHD_MCP_server: Instructions file for Codex

EODHD MCP Server v1

MCP server exposing 75 EODHD financial data API tools via HTTP, SSE, and stdio transports.

Stack

Python 3.10+, FastMCP >=2.0, httpx (async HTTP), Ruff, MyPy, pytest, Bandit, Semgrep, pip-audit

Commands

pytest tests/auto/ -v --tb=short                         # run auto
pytest tests/auto/ -v --cov=app --cov-report=term-missing  # with coverage
ruff check app/ server.py                                # lint
ruff format --check app/ server.py                       # format check
mypy app/ server.py --ignore-missing-imports --explicit-package-bases  # type check
bandit -r app/ -ll -ii -x app/resources/                 # security scan (AST)
semgrep scan --config p/python --config p/owasp-top-ten --config p/secrets --config p/jwt --error app/  # SAST + taint
python server.py                                         # run (HTTP, port 8000)
python server.py --stdio                                 # run (stdio)

Architecture

• server.py — entry point, transport selection
• app/config.py — env vars, API base URL
• app/api_client.py — shared async httpx client with retry, rate-limit, auth injection
• app/input_formatter.py — input sanitisation (ticker, exchange) and date coercion
• app/response_formatter.py — MCP EmbeddedResource formatting and API error raising
• app/tools/ — 75 tool modules, each exports register(mcp: FastMCP)
• app/tools/__init__.py — ALL_TOOLS list, register_all(mcp), safe dynamic import
• app/prompts/ — example workflows
• app/resources/ — markdown reference docs as MCP resources

Key Rules

• Every tool file must export register(mcp) — called by register_all()
• All tools are read-only (readOnlyHint=True)
• Sanitise inputs via sanitize_ticker(), sanitize_exchange() from app/input_formatter.py (only reject URL-breaking chars; let API validate)
• Raise ToolError for user-facing errors
• Return via response_formatter (format_json_response, format_text_response, format_binary_response)
• Preserve explicit upstream API errors; do not silently pass through {"error": ...} payloads as successful results
• All HTTP calls go through make_request() in api_client.py — never call httpx directly
• No cross-tool imports (tools must not import from other tool modules)
• No print() in app code — use logging
• Use X | None not Optional[X]