diff --git a/src/agentCore.jl b/src/agentCore.jl
index 7e1022d..ab0d5f4 100644
--- a/src/agentCore.jl
+++ b/src/agentCore.jl
@@ -310,13 +310,13 @@ function _agentLoop(agent::yiemAgent)
             else  # _processMessage() done and no followUp message.
               agent.agentEventSink("_agentLoop 4 agent._state.messages length $(length(agent._state.messages))")
               result = deepcopy(agent._state.messages[end])
-
+              agent.agentEventSink("_agentLoop 4-1 ")
               # filter out reasoningContent in-place
               filter!(c -> !(c isa reasoningContent), result.content)
-
+              agent.agentEventSink("_agentLoop 5 ")
               # format output
               respondToUI = _assistantMessageToOpenAI(result)
-
+              agent.agentEventSink("_agentLoop 6 ")
               put!(agent.outputChannel, respondToUI)
               if !isempty(result.content) && result.content[1] isa textContent
                 agent.agentEventSink(result.content[1].text)
@@ -376,6 +376,13 @@ function _agentLoop(agent::yiemAgent)
       end
     end
   catch e
+    bt = catch_backtrace()
+    errMsg = sprint() do io
+        showerror(io, e, bt)
+        println(io)
+    end
+    agentEventSink(errMsg)
+
     # On any error, send error response and exit the loop
     @error "Agent loop failed" error=e
   end
@@ -1085,13 +1092,12 @@ function executePreparedToolCall(
     llmCall::Union{Any,Nothing}=nothing,
   )::executedOutcome
   agentEventSink("executePreparedToolCall 1")
-  agentEventSink("executePreparedToolCall 2")
-  agentEventSink("executePreparedToolCall 3")
 
-  try
+  try #WORKING
     result = prep.tool.execute(prep.toolCall.id, prep.args, signal, agentEventSink, llmCall)
+    agentEventSink("executePreparedToolCall 2")
     agentEventSink(result.content[1].text)
-    agentEventSink("executePreparedToolCall 4")
+    agentEventSink("executePreparedToolCall 3")
     return executedOutcome(result, false)
   catch e
     bt = catch_backtrace()
diff --git a/src/toolRegistry.jl b/src/toolRegistry.jl
index 26e56b7..8381d2e 100644
--- a/src/toolRegistry.jl
+++ b/src/toolRegistry.jl
@@ -100,7 +100,7 @@ function _wrap_mcp_tool(mcpserver, tool_def::Dict{String,Any})::agentTool
         inputSchema=params,
         execute=(toolCallId::String, args::Dict{String,Any},
                  signal::Union{Nothing,abortSignal},
-                 onPartialResult::Function,
+                 agentEventSink,
                  llmCall=nothing) -> begin
             try
                 response = mcpserver("tools/call", name, args)
@@ -256,7 +256,7 @@ function listTool(store::toolStore, mcpserver)::agentTool
         ),
         execute=(toolCallId::String, args::Dict{String,Any},
                  signal::Union{Nothing,abortSignal},
-                 onPartialResult::Function, llmCall=nothing) -> begin
+                 agentEventSink, llmCall=nothing) -> begin
             # Discover and register MCP tools (idempotent — skips already registered)
             new_count, tool_list = _register_mcp_tools(mcpserver, store)
 
diff --git a/test/toolTest.jl b/test/toolTest.jl
deleted file mode 100644
index f613397..0000000
--- a/test/toolTest.jl
+++ /dev/null
@@ -1,367 +0,0 @@
-using Test
-using Dates
-using YiemAgent
-using YiemAgent.toolRegistry
-using YiemAgent.type
-using YiemAgent.agentCore
-
-@testset "register_all_tools with toolStore" begin
-
-    # ------------------------------------------------------------------ #
-    # 1. register_all_tools registers all static tools + listTools       #
-    # ------------------------------------------------------------------ #
-    store = toolStore(name="test1")
-    loaded = register_all_tools(store)
-    @test !isempty(loaded)
-    @test length(loaded) == 4  # getWeather + getTime + writeTool + listTools
-
-    names = [k for k in keys(loaded)]
-    @test "getTime" in names
-    @test "getWeather" in names
-    @test "writeTool" in names
-    @test "listTools" in names
-
-    # ------------------------------------------------------------------ #
-    # 2. register_all_tools returns tools in registration order          #
-    # ------------------------------------------------------------------ #
-    @test collect(keys(loaded))[1] == "getWeather"
-    @test collect(keys(loaded))[2] == "getTime"
-    @test collect(keys(loaded))[3] == "writeTool"
-    @test collect(keys(loaded))[4] == "listTools"
-
-    # ------------------------------------------------------------------ #
-    # 3. Verify loaded tool fields are correct                           #
-    # ------------------------------------------------------------------ #
-    # getTime
-    time_tool = loaded["getTime"]
-    @test time_tool.name == "getTime"
-    @test time_tool.label == "Time Lookup"
-    @test time_tool.validateRequiredArgs !== nothing
-    @test time_tool.parallelToolExecute == false
-    @test time_tool.inputSchema["required"] == Any[]
-
-    # getWeather
-    weather = loaded["getWeather"]
-    @test weather.name == "getWeather"
-    @test weather.label == "Weather Lookup"
-    @test weather.execute !== nothing
-    @test weather.parallelToolExecute == false
-    @test weather.inputSchema["required"] == ["city"]
-
-    # writeTool
-    wt = loaded["writeTool"]
-    @test wt.name == "writeTool"
-    @test wt.label == "Create Tool"
-    @test wt.execute !== nothing
-    @test "name" in wt.inputSchema["required"]
-    @test "executeCode" in wt.inputSchema["required"]
-
-    # ------------------------------------------------------------------ #
-    # 4. Tool execution returns valid results                            #
-    # ------------------------------------------------------------------ #
-    sig = nothing
-    op = x -> x  # no-op partial result callback
-
-    # execute getTime
-    result_t = time_tool.execute("call-1", Dict{String,Any}("city" => "Tokyo"), sig, op)
-    @test result_t isa agentToolResult
-    @test result_t.content[1] isa textContent
-    @test occursin("Tokyo", result_t.content[1].text)
-
-    # execute getTime with timezone
-    result_tz = time_tool.execute("call-2", Dict{String,Any}("timezone" => "America/New_York"), sig, op)
-    @test result_tz isa agentToolResult
-    @test occursin("America/New_York", result_tz.content[1].text)
-
-    # execute getWeather
-    result_w = weather.execute("call-3", Dict{String,Any}("city" => "Bangkok"), sig, op)
-    @test result_w isa agentToolResult
-    @test result_w.content[1] isa textContent
-    @test occursin("Bangkok", result_w.content[1].text)
-
-    # execute getWeather with units
-    result_w2 = weather.execute("call-4", Dict{String,Any}("city" => "London", "units" => "fahrenheit"), sig, op)
-    @test occursin("72\u00b0F", result_w2.content[1].text)
-
-    # ------------------------------------------------------------------ #
-    # 5. getTools / registerTool / clearTools (per-store isolation)      #
-    # ------------------------------------------------------------------ #
-    store3 = toolStore(name="test3")
-    registry_tools = getTools(store3)
-    @test isempty(registry_tools)
-
-    # Register tools manually
-    registerTool(store3, loaded["getTime"])
-    registerTool(store3, loaded["getWeather"])
-    registerTool(store3, loaded["writeTool"])
-
-    reg = getTools(store3)
-    @test !isempty(reg)
-    @test "getTime" in keys(reg)
-    @test "getWeather" in keys(reg)
-    @test "writeTool" in keys(reg)
-    @test collect(keys(reg))[1] == "getTime"
-    @test collect(keys(reg))[2] == "getWeather"
-    @test collect(keys(reg))[3] == "writeTool"
-
-    clearTools(store3)
-    @test isempty(getTools(store3))
-
-    test_tool = agentTool(
-        name = "manualTool",
-        label = "Manual Tool",
-        description = "Registered manually",
-        inputSchema = Dict{String,Any}("type" => "object", "properties" => Dict{String,Any}(), "required" => Any[]),
-        execute = (toolCallId, args, signal, onPartialResult) ->
-            agentToolResult([textContent("manual")], Dict{Any,Any}(), nothing, false),
-        prepareArguments = nothing,
-        validateRequiredArgs = nothing,
-        parallelToolExecute = true
-    )
-    registerTool(store3, test_tool)
-    reg = getTools(store3)
-    @test haskey(reg, "manualTool")
-    @test length(reg) == 1
-    @test reg["manualTool"].parallelToolExecute == true
-
-    # ------------------------------------------------------------------ #
-    # 6. getTools returns direct reference (mutations affect registry)   #
-    # ------------------------------------------------------------------ #
-    copy1 = getTools(store3)
-    copy2 = getTools(store3)
-    @test copy1 === copy2  # same reference, not a deep copy
-    empty!(copy1)
-    @test isempty(getTools(store3))  # mutation propagates
-
-    # ------------------------------------------------------------------ #
-    # 7. Per-store isolation — two stores don't share tools              #
-    # ------------------------------------------------------------------ #
-    storeA = toolStore(name="isolationA")
-    storeB = toolStore(name="isolationB")
-
-    registerTool(storeA, loaded["getTime"])
-    registerTool(storeB, loaded["getWeather"])
-
-    regA = getTools(storeA)
-    regB = getTools(storeB)
-
-    @test "getTime" in keys(regA)
-    @test "getWeather" ∉ keys(regA)
-    @test "getWeather" in keys(regB)
-    @test "getTime" ∉ keys(regB)
-
-    clearTools(storeA)
-    @test isempty(getTools(storeA))
-    @test !isempty(getTools(storeB))  # storeB unaffected
-end
-
-@testset "listTool" begin
-    store = toolStore(name="test_list")
-    register_all_tools(store)  # auto-registers getWeather, getTime, writeTool + listTools
-
-    # register_all_tools auto-registers listTool
-    @test "listTools" in keys(store.tools)
-
-    # listTool returns an agentTool, not a string or array
-    list_t = listTool(store)
-    @test list_t isa agentTool
-    @test list_t.name == "listTools"
-    @test list_t.label == "List Tools"
-    @test isempty(list_t.inputSchema["required"])
-
-    # Verify all tools appear (3 loaded + listTools = 4)
-    result = list_t.execute("call-1", Dict{String,Any}(), nothing, x -> x)
-    @test result isa agentToolResult
-    @test result.content[1] isa textContent
-    @test occursin("listTools", result.content[1].text)
-    @test occursin("getWeather", result.content[1].text)
-    @test occursin("getTime", result.content[1].text)
-    @test occursin("writeTool", result.content[1].text)
-    @test result.details["count"] == 4
-
-    # Each listTool call creates an independent closure
-    storeB = toolStore(name="test_listB")
-    registerTool(storeB, store.tools["getWeather"])
-    list_tB = listTool(storeB)
-
-    resultA = list_t.execute("call-3", Dict{String,Any}(), nothing, x -> x)
-    resultB = list_tB.execute("call-4", Dict{String,Any}(), nothing, x -> x)
-
-    @test occursin("getWeather", resultA.content[1].text)
-    @test occursin("getWeather", resultB.content[1].text)
-    @test occursin("getTime", resultA.content[1].text)
-    @test occursin("getTime", resultB.content[1].text) == false  # storeB only has getWeather
-end
-
-@testset "executePreparedToolCall with static tools" begin
-    # Tests executePreparedToolCall with statically loaded tools.
-    # The world-age issue is resolved because tool.execute comes from
-    # a statically included module, not a dynamically created one.
-
-    store = toolStore(name="test_static")
-    register_all_tools(store)
-
-    weather_tool = store.tools["getWeather"]
-
-    # Create a preparedToolCall that mimics what prepareToolCall() returns
-    tool_call = agentToolCall(
-        "function", "call-static-1", "getWeather",
-        Dict{String,Any}("city" => "San Francisco")
-    )
-    prep = preparedToolCall(
-        weather_tool, tool_call, Dict{String,Any}("city" => "San Francisco")
-    )
-    sig = abortSignal(false)
-
-    # This call goes through: executePreparedToolCall -> prep.tool.execute(...)
-    result = executePreparedToolCall(
-        prep, sig, x -> nothing
-    )
-
-    @test result isa executedOutcome
-    @test result.isError == false
-    @test result.result.content[1] isa textContent
-    @test occursin("San Francisco", result.result.content[1].text)
-end
-
-@testset "executePreparedToolCall with validation (static tools)" begin
-    # Tests executePreparedToolCall with a tool that has custom validation hooks.
-    # This exercises the full tool execution path including validation.
-
-    store = toolStore(name="test_static_validate")
-    register_all_tools(store)
-
-    time_tool = store.tools["getTime"]
-
-    tool_call = agentToolCall(
-        "function", "call-static-2", "getTime",
-        Dict{String,Any}("timezone" => "America/New_York")
-    )
-    prep = preparedToolCall(
-        time_tool, tool_call, Dict{String,Any}("timezone" => "America/New_York")
-    )
-    sig = abortSignal(false)
-
-    result = executePreparedToolCall(
-        prep, sig, x -> nothing
-    )
-
-    @test result isa executedOutcome
-    @test result.isError == false
-    @test result.result.content[1] isa textContent
-    @test occursin("America/New_York", result.result.content[1].text)
-end
-
-@testset "executeToolCallsSequential with static tools (full pipeline)" begin
-    # Tests the full tool execution pipeline: executeToolCallsSequential
-    # which calls prepareToolCall -> executePreparedToolCall -> finalizeExecutedToolCall
-    # with statically loaded tools.
-
-    store = toolStore(name="test_full_pipeline")
-    register_all_tools(store)
-
-    # Build agentContext from the store's tools
-    tools = getTools(store)
-    ctx = agentContext(
-        "test system prompt",
-        agentMessage[],
-        tools
-    )
-
-    # Create an assistant message containing tool calls
-    assistant_msg = assistantMessage(
-        role="assistant",
-        content=Vector{messageContent}(),
-        api="openai",
-        provider="test",
-        model="test-model",
-        usage=llmUsage(0, 0),
-        stopReason="tool_calls",
-        errorMessage=nothing,
-        timestamp=now()
-    )
-
-    # Create tool calls for multiple statically loaded tools
-    tool_calls = [
-        agentToolCall(
-            "function", "call-seq-1", "getWeather",
-            Dict{String,Any}("city" => "Tokyo")
-        ),
-        agentToolCall(
-            "function", "call-seq-2", "getTime",
-            Dict{String,Any}("timezone" => "Europe/London")
-        ),
-    ]
-
-    config = agentLoopConfig(
-        nothing, nothing, "sequential"
-    )
-    sig = abortSignal(false)
-
-    # Execute the full pipeline
-    batch = executeToolCallsSequential(
-        ctx, assistant_msg, tool_calls, config, sig, x -> nothing
-    )
-
-    @test batch.messages isa Vector{toolResultMessage}
-    @test length(batch.messages) == 2
-    @test batch.messages[1].toolName == "getWeather"
-    @test batch.messages[1].isError == false
-    @test occursin("Tokyo", batch.messages[1].content[1].text)
-    @test batch.messages[2].toolName == "getTime"
-    @test batch.messages[2].isError == false
-    @test occursin("Europe/London", batch.messages[2].content[1].text)
-end
-
-@testset "executeToolCallsParallel with static tools (full pipeline)" begin
-    # Same as above but tests parallel execution path.
-
-    store = toolStore(name="test_parallel")
-    register_all_tools(store)
-
-    tools = getTools(store)
-    ctx = agentContext(
-        "test system prompt",
-        agentMessage[],
-        tools
-    )
-
-    assistant_msg = assistantMessage(
-        role="assistant",
-        content=Vector{messageContent}(),
-        api="openai",
-        provider="test",
-        model="test-model",
-        usage=llmUsage(0, 0),
-        stopReason="tool_calls",
-        errorMessage=nothing,
-        timestamp=now()
-    )
-
-    tool_calls = [
-        agentToolCall(
-            "function", "call-par-1", "getWeather",
-            Dict{String,Any}("city" => "Paris")
-        ),
-        agentToolCall(
-            "function", "call-par-2", "getTime",
-            Dict{String,Any}("city" => "Sydney")
-        ),
-    ]
-
-    config = agentLoopConfig(
-        nothing, nothing, "parallel"
-    )
-    sig = abortSignal(false)
-
-    batch = executeToolCallsParallel(
-        ctx, assistant_msg, tool_calls, config, sig, x -> nothing
-    )
-
-    @test batch.messages isa Vector{toolResultMessage}
-    @test length(batch.messages) == 2
-    @test batch.messages[1].toolName == "getWeather"
-    @test batch.messages[1].isError == false
-    @test batch.messages[2].toolName == "getTime"
-    @test batch.messages[2].isError == false
-end