[bot] Spring AI tool/function execution produces no span — only the surrounding chat model call is traced

[braintrust-bot]

Summary

Both Spring AI instrumentation modules (springai_1_0_0, springai_2_0_0) only wrap OpenAiChatModel.Builder/AnthropicChatModel.Builder construction (BraintrustSpringAI.wrap()). Spring AI's own local tool-execution machinery — ToolCallingManager/DefaultToolCallingManager, the auto-registered ToolCallingAdvisor, and ToolCallback/MethodToolCallback/FunctionToolCallback — is never touched by either module. When a model response triggers a tool call, Spring AI resolves and invokes the corresponding Java method in-process, but that invocation produces no span: only the LLM call that requested the tool and the follow-up LLM call that consumes the result are traced, with the actual tool execution invisible in between.

This is distinct from the already-filed streaming-reassembly bugs (#78 Anthropic SSE tool_use/thinking blocks, #79 OpenAI SSE tool_calls delta-merging) — those are about the LLM span's own tool_calls output being malformed during streaming. This gap is about the absence of a separate span for the tool's actual execution, which is the "tool-calling during model execution" surface itself, comparable to langchain_1_8_0's TracingToolExecutor which does instrument LangChain4j's equivalent local tool execution.

What is missing

A full-repo search for ToolCalling, ToolCallback, and toolCall under both springai_1_0_0 and springai_2_0_0 returns zero matches. BraintrustSpringAI.java in both modules exposes exactly one entry point:

public static <T> T wrap(OpenTelemetry openTelemetry, T chatModelBuilder) { ... }

which only instruments chat model construction. Neither module registers any instrumentation for:

• ToolCallingManager.executeToolCalls() — the method that actually resolves and invokes tool callbacks in response to a model's tool-call request
• ToolCallingAdvisor — the ChatClient advisor auto-registered whenever tools are present, which drives the resolve/execute loop
• ToolCallback.call() (and its MethodToolCallback/FunctionToolCallback implementations) — the actual per-tool invocation point

For comparison, langchain_1_8_0 instruments LangChain4j's analogous local-execution surface via TracingToolExecutor, producing a dedicated span per tool call — Spring AI has no equivalent.

Braintrust docs status

• Spring AI integration is not documented on Braintrust's integrations page at https://www.braintrust.dev/docs/integrations/ai-providers: not_found
• Braintrust's general tracing docs (https://www.braintrust.dev/docs/instrument/trace-llm-calls) describe function/tool calling as part of LLM span capture, not as a separately-spanned execution step: not_found for a documented tool-execution span pattern this gap would need to follow

Upstream sources

• Spring AI tool calling reference: https://docs.spring.io/spring-ai/reference/api/tools.html — documents ToolCallingManager, ToolCallingAdvisor (auto-registered in the ChatClient advisor chain), and ToolCallback/MethodToolCallback/FunctionToolCallback as the current (Spring AI 1.x/2.x) tool-execution architecture
• Spring AI OpenAI chat reference: https://docs.spring.io/spring-ai/reference/api/chat/openai-chat.html — confirms function/tool calling support for the exact provider this repo already instruments

Local files inspected

• braintrust-sdk/instrumentation/springai_1_0_0/src/main/java/dev/braintrust/instrumentation/springai/v1_0_0/BraintrustSpringAI.java — single wrap(OpenTelemetry, T chatModelBuilder) entry point (line 61); no tool-calling instrumentation
• braintrust-sdk/instrumentation/springai_1_0_0/src/main/java/dev/braintrust/instrumentation/springai/v1_0_0/auto/SpringAIOpenAIInstrumentationModule.java and SpringAIAnthropicInstrumentationModule.java — only instrument the two chat model builders
• braintrust-sdk/instrumentation/springai_2_0_0/src/main/java/dev/braintrust/instrumentation/springai/v2_0_0/BraintrustSpringAI.java, SpringAIOpenAI.java, SpringAIAnthropic.java, and their auto/*InstrumentationModule.java — same scope as 1.0.0, no tool-calling instrumentation
• Full-repo grep for ToolCalling, ToolCallback, toolCall scoped to both Spring AI modules — zero matches
• braintrust-sdk/instrumentation/langchain_1_8_0/ — confirmed as the comparison point: this module does instrument LangChain4j's equivalent local tool-execution surface (TracingToolExecutor)