Lazy mcp client and toolcallback resolution #4671
Open
+1,466
−158
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Resolves critical timing issues in MCP client initialization and
tool callback resolution that prevented proper registration of
MCP-annotated beans.
- MCP clients created after all singleton beans initialized
- Implement SmartInitializingSingleton for deferred client creation
via McpSyncClientInitializer and McpAsyncClientInitializer
- Tool callbacks resolved at execution instead configuration
- Store ToolCallbackProvider instances in ChatClient and resolve
lazily at execution time (call/stream)
- Filter MCP providers from StaticToolCallbackResolver
- Inconsistent list reference handling
- Add mcpClientsReference() methods for proper reference sharing
Breaking Changes:
- MCP providers no longer in static resolver (transparent)
- Client creation timing changed (transparent)
Fixes: spring-projects#4670, spring-projects#4618
Signed-off-by: Christian Tzolov <christian.tzolov@broadcom.com>
tzolov
force-pushed
the
lazy-mcp-client-and-toolcallback-resolution-2
branch
from
98ad131 to
2b8bd13
Compare
jiafu1115
reviewed
Oct 20, 2025
| .toolContextToMcpMetaConverter( | ||
| toolContextToMcpMetaConverter.getIfUnique(() -> ToolContextToMcpMetaConverter.defaultConverter())) | ||
| .mcpClients(mcpClients) | ||
| .mcpClientsReference(mcpClients) |
There was a problem hiding this comment.
if it can use clients instead of mcpClients. after all. the mcpClients is deprecated and mcpClientsReference is too long
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fixes critical timing issues where MCP clients were created before all annotated beans were scanned, and tool callbacks were resolved too early during ChatClient configuration.
Problems Fixed
Solution
McpSyncClientInitializerandMcpAsyncClientInitializerclasses defer client creation until after all singletons are instantiatedcall()/stream())StaticToolCallbackResolverto enable lazy resolutionmcpClientsReference()methods to properly share list referencesKey Changes
Configuration:
McpClientAutoConfiguration.java- Added initializer classesMcpToolCallbackAutoConfiguration.java- Uses reference sharingMcpClientSpecificationFactoryAutoConfiguration.java- Deprecated (disabled by default)Tool Resolution:
DefaultChatClient.java- Lazy provider resolutionToolCallingAutoConfiguration.java- MCP provider filteringProviders:
mcpClientsReference()toSyncMcpToolCallbackProviderandAsyncMcpToolCallbackProviderBreaking Changes
Deprecated (still functional):
mcpClients(List)andmcpClients(varargs)→ UsemcpClientsReference(List)insteadBehavioral (transparent to users):
Migration
Most users: No changes required - fixes are transparent and backward compatible.
Custom MCP providers: Update to use
mcpClientsReference()instead of deprecatedmcpClients()methods.Resolves: #4670, #4618