rohitg00/ai-engineering-from-scratch · error · ContractViolation

tools/list page limit must be a positive integer

Error message

tools/list page limit must be a positive integer

What it means

Error "tools/list page limit must be a positive integer" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at phases/13-tools-and-protocols/28-mcp-tool-contracts-and-content/code/main.py:680

                        "error": {
                            "code": -32020,
                            "message": "parameter headers do not match request body",
                            "data": {"reason": str(exc)},
                        },
                    }
    return 200, server.dispatch(request, principal=principal)


class ContractClient:
    def __init__(
        self,
        server: ContractServer,
        *,
        principal: str = "analyst",
        max_list_pages: int = MAX_TOOL_LIST_PAGES,
    ) -> None:
        if type(max_list_pages) is not int or max_list_pages <= 0:
            raise ContractViolation("tools/list page limit must be a positive integer")
        self.server = server
        self.principal = principal
        self.max_list_pages = max_list_pages
        self.rejections: list[dict[str, str]] = []
        self.cursor_trace: list[str | None] = []
        self.tools: dict[str, dict[str, Any]] = {}

    def discover_tools(self) -> dict[str, dict[str, Any]]:
        cursor: str | None = None
        request_id = 1
        seen_cursors: set[str] = set()
        for _ in range(self.max_list_pages):
            params: dict[str, Any] = {}
            if cursor is not None:
                params["cursor"] = cursor
            self.cursor_trace.append(cursor)
            response = self.server.dispatch(make_request(request_id, "tools/list", params))
            if response is None or "error" in response:

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at phases/13-tools-and-protocols/28-mcp-tool-contracts-and-content/code/main.py:680 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/42d4c22921a5959e. Report an issue: GitHub.