105 lines
3.5 KiB
Python
105 lines
3.5 KiB
Python
"""
|
|
Shared validation functions for server requests.
|
|
|
|
This module provides validation logic for sampling and elicitation requests
|
|
that is shared across normal and task-augmented code paths.
|
|
"""
|
|
|
|
from mcp.shared.exceptions import McpError
|
|
from mcp.types import (
|
|
INVALID_PARAMS,
|
|
ClientCapabilities,
|
|
ErrorData,
|
|
SamplingMessage,
|
|
Tool,
|
|
ToolChoice,
|
|
)
|
|
|
|
|
|
def check_sampling_tools_capability(client_caps: ClientCapabilities | None) -> bool:
|
|
"""
|
|
Check if the client supports sampling tools capability.
|
|
|
|
Args:
|
|
client_caps: The client's declared capabilities
|
|
|
|
Returns:
|
|
True if client supports sampling.tools, False otherwise
|
|
"""
|
|
if client_caps is None:
|
|
return False
|
|
if client_caps.sampling is None:
|
|
return False
|
|
if client_caps.sampling.tools is None:
|
|
return False
|
|
return True
|
|
|
|
|
|
def validate_sampling_tools(
|
|
client_caps: ClientCapabilities | None,
|
|
tools: list[Tool] | None,
|
|
tool_choice: ToolChoice | None,
|
|
) -> None:
|
|
"""
|
|
Validate that the client supports sampling tools if tools are being used.
|
|
|
|
Args:
|
|
client_caps: The client's declared capabilities
|
|
tools: The tools list, if provided
|
|
tool_choice: The tool choice setting, if provided
|
|
|
|
Raises:
|
|
McpError: If tools/tool_choice are provided but client doesn't support them
|
|
"""
|
|
if tools is not None or tool_choice is not None:
|
|
if not check_sampling_tools_capability(client_caps):
|
|
raise McpError(
|
|
ErrorData(
|
|
code=INVALID_PARAMS,
|
|
message="Client does not support sampling tools capability",
|
|
)
|
|
)
|
|
|
|
|
|
def validate_tool_use_result_messages(messages: list[SamplingMessage]) -> None:
|
|
"""
|
|
Validate tool_use/tool_result message structure per SEP-1577.
|
|
|
|
This validation ensures:
|
|
1. Messages with tool_result content contain ONLY tool_result content
|
|
2. tool_result messages are preceded by a message with tool_use
|
|
3. tool_result IDs match the tool_use IDs from the previous message
|
|
|
|
See: https://github.com/modelcontextprotocol/modelcontextprotocol/issues/1577
|
|
|
|
Args:
|
|
messages: The list of sampling messages to validate
|
|
|
|
Raises:
|
|
ValueError: If the message structure is invalid
|
|
"""
|
|
if not messages:
|
|
return
|
|
|
|
last_content = messages[-1].content_as_list
|
|
has_tool_results = any(c.type == "tool_result" for c in last_content)
|
|
|
|
previous_content = messages[-2].content_as_list if len(messages) >= 2 else None
|
|
has_previous_tool_use = previous_content and any(c.type == "tool_use" for c in previous_content)
|
|
|
|
if has_tool_results:
|
|
# Per spec: "SamplingMessage with tool result content blocks
|
|
# MUST NOT contain other content types."
|
|
if any(c.type != "tool_result" for c in last_content):
|
|
raise ValueError("The last message must contain only tool_result content if any is present")
|
|
if previous_content is None:
|
|
raise ValueError("tool_result requires a previous message containing tool_use")
|
|
if not has_previous_tool_use:
|
|
raise ValueError("tool_result blocks do not match any tool_use in the previous message")
|
|
|
|
if has_previous_tool_use and previous_content:
|
|
tool_use_ids = {c.id for c in previous_content if c.type == "tool_use"}
|
|
tool_result_ids = {c.toolUseId for c in last_content if c.type == "tool_result"}
|
|
if tool_use_ids != tool_result_ids:
|
|
raise ValueError("ids of tool_result blocks and tool_use blocks from previous message do not match")
|