forked from HAL9000/cleveragents-core
freemo
b96138b88e
MCPToolAdapter.invoke() was reading error messages from result.get('error',
'unknown error'), but the MCP 1.4.0 protocol returns errors in the content
field as a list of content items with type and text keys. This caused every
error from a real MCP 1.4.0-compliant server to be silently replaced with
the string 'unknown error'.
Changes:
- src/cleveragents/mcp/adapter.py: extract error_text from content[0].text
with safe guards (isinstance check, length check) and fallback to
'unknown error' when content is absent or empty
- features/mocks/mock_mcp_transport.py: return MCP 1.4.0-compliant error
responses using content list format instead of the non-standard error key
- features/tdd_mcp_error_content_key.feature: Behave scenario verifying
correct error extraction from MCP 1.4.0 content arrays (written as TDD
issue-capture, @tdd_expected_fail removed after fix applied)
- features/steps/tdd_mcp_error_content_key_steps.py: step definitions for
the new scenario including _MCP14ErrorTransport mock subclass
All 51 MCP adapter scenarios pass. Typecheck: 0 errors. Lint: clean.
ISSUES CLOSED: #2158
72 lines
2.6 KiB
Python
72 lines
2.6 KiB
Python
"""Step definitions for features/tdd_mcp_error_content_key.feature.
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TDD issue-capture scenario for #2158: MCPToolAdapter.invoke() must extract
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error messages from content[0].text per MCP 1.4.0 protocol.
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"""
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from __future__ import annotations
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from typing import Any
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from behave import given, then
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from behave.runner import Context
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from cleveragents.mcp.adapter import MCPServerConfig, MCPToolAdapter
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from features.mocks.mock_mcp_transport import MockMCPTransport
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class _MCP14ErrorTransport(MockMCPTransport):
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"""Mock transport that returns MCP 1.4.0-compliant error responses.
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Returns ``{"isError": True, "content": [{"type": "text", "text": "..."}]}``
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instead of the non-standard ``{"isError": True, "error": "..."}`` format.
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"""
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def __init__(self, tool_name: str, error_text: str) -> None:
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tools = [
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{
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"name": tool_name,
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"description": f"Mock tool {tool_name}",
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"inputSchema": {},
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}
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]
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super().__init__(tools=tools)
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self._mcp14_error_tool = tool_name
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self._mcp14_error_text = error_text
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def call(self, method: str, params: dict[str, Any]) -> dict[str, Any]:
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if method == "tools/call":
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tool_name = params.get("name", "")
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if tool_name == self._mcp14_error_tool:
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return {
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"isError": True,
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"content": [{"type": "text", "text": self._mcp14_error_text}],
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}
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return super().call(method, params)
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@given(
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'a connected MCP adapter with a tool returning MCP 1.4.0 content-based error "{tool_name}"'
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)
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def step_mcp14_error_tool(context: Context, tool_name: str) -> None:
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"""Set up a connected MCP adapter whose tool returns a MCP 1.4.0 content-based error."""
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transport = _MCP14ErrorTransport(
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tool_name=tool_name,
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error_text="File not found: /path/to/file",
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)
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config = MCPServerConfig(name="test-server", transport="stdio", command="echo")
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context.mcp_adapter = MCPToolAdapter(config=config, transport=transport)
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context.mcp_adapter.connect()
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context.mcp_adapter.discover_tools()
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@then('the invocation error should contain "{expected}"')
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def step_invoke_error_contains(context: Context, expected: str) -> None:
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"""Assert the invocation error message contains the expected substring."""
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result = context.mcp_invoke_result
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assert result is not None, "No invocation result found"
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assert result.error is not None, "Expected an error but got None"
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assert expected in result.error, (
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f"Expected error to contain {expected!r}, got: {result.error!r}"
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)
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