diff --git a/apps/sim/executor/execution/block-executor.ts b/apps/sim/executor/execution/block-executor.ts
index f159e4db0..e73f57323 100644
--- a/apps/sim/executor/execution/block-executor.ts
+++ b/apps/sim/executor/execution/block-executor.ts
@@ -28,6 +28,7 @@ import type {
 } from '@/executor/types'
 import { streamingResponseFormatProcessor } from '@/executor/utils'
 import { buildBlockExecutionError, normalizeError } from '@/executor/utils/errors'
+import { isJSONString } from '@/executor/utils/json'
 import { filterOutputForLog } from '@/executor/utils/output-filter'
 import { validateBlockType } from '@/executor/utils/permission-check'
 import type { VariableResolver } from '@/executor/variables/resolver'
@@ -86,7 +87,7 @@ export class BlockExecutor {
       resolvedInputs = this.resolver.resolveInputs(ctx, node.id, block.config.params, block)
 
       if (blockLog) {
-        blockLog.input = resolvedInputs
+        blockLog.input = this.parseJsonInputs(resolvedInputs)
       }
     } catch (error) {
       cleanupSelfReference?.()
@@ -157,7 +158,14 @@ export class BlockExecutor {
         const displayOutput = filterOutputForLog(block.metadata?.id || '', normalizedOutput, {
           block,
         })
-        this.callOnBlockComplete(ctx, node, block, resolvedInputs, displayOutput, duration)
+        this.callOnBlockComplete(
+          ctx,
+          node,
+          block,
+          this.parseJsonInputs(resolvedInputs),
+          displayOutput,
+          duration
+        )
       }
 
       return normalizedOutput
@@ -233,7 +241,7 @@ export class BlockExecutor {
       blockLog.durationMs = duration
       blockLog.success = false
       blockLog.error = errorMessage
-      blockLog.input = input
+      blockLog.input = this.parseJsonInputs(input)
       blockLog.output = filterOutputForLog(block.metadata?.id || '', errorOutput, { block })
     }
 
@@ -248,7 +256,14 @@ export class BlockExecutor {
 
     if (!isSentinel) {
       const displayOutput = filterOutputForLog(block.metadata?.id || '', errorOutput, { block })
-      this.callOnBlockComplete(ctx, node, block, input, displayOutput, duration)
+      this.callOnBlockComplete(
+        ctx,
+        node,
+        block,
+        this.parseJsonInputs(input),
+        displayOutput,
+        duration
+      )
     }
 
     const hasErrorPort = this.hasErrorPortEdge(node)
@@ -336,6 +351,36 @@ export class BlockExecutor {
     return { result: output }
   }
 
+  /**
+   * Parse JSON string inputs to objects for log display only.
+   * Attempts to parse any string that looks like JSON.
+   * Returns a new object - does not mutate the original inputs.
+   */
+  private parseJsonInputs(inputs: Record<string, any>): Record<string, any> {
+    let result = inputs
+    let hasChanges = false
+
+    for (const [key, value] of Object.entries(inputs)) {
+      // isJSONString is a quick heuristic (checks for { or [), not a validator.
+      // Invalid JSON is safely caught below - this just avoids JSON.parse on every string.
+      if (typeof value !== 'string' || !isJSONString(value)) {
+        continue
+      }
+
+      try {
+        if (!hasChanges) {
+          result = { ...inputs }
+          hasChanges = true
+        }
+        result[key] = JSON.parse(value.trim())
+      } catch {
+        // Not valid JSON, keep original string
+      }
+    }
+
+    return result
+  }
+
   private callOnBlockStart(ctx: ExecutionContext, node: DAGNode, block: SerializedBlock): void {
     const blockId = node.id
     const blockName = block.metadata?.name ?? blockId
diff --git a/apps/sim/executor/handlers/agent/agent-handler.ts b/apps/sim/executor/handlers/agent/agent-handler.ts
index 6c0d19fc3..a22f7a8c4 100644
--- a/apps/sim/executor/handlers/agent/agent-handler.ts
+++ b/apps/sim/executor/handlers/agent/agent-handler.ts
@@ -936,8 +936,8 @@ export class AgentBlockHandler implements BlockHandler {
       systemPrompt: validMessages ? undefined : inputs.systemPrompt,
       context: validMessages ? undefined : stringifyJSON(messages),
       tools: formattedTools,
-      temperature: inputs.temperature,
-      maxTokens: inputs.maxTokens,
+      temperature: inputs.temperature != null ? Number(inputs.temperature) : undefined,
+      maxTokens: inputs.maxTokens != null ? Number(inputs.maxTokens) : undefined,
       apiKey: inputs.apiKey,
       azureEndpoint: inputs.azureEndpoint,
       azureApiVersion: inputs.azureApiVersion,
diff --git a/apps/sim/providers/azure-openai/index.ts b/apps/sim/providers/azure-openai/index.ts
index f912e92be..195103ffe 100644
--- a/apps/sim/providers/azure-openai/index.ts
+++ b/apps/sim/providers/azure-openai/index.ts
@@ -102,7 +102,7 @@ export const azureOpenAIProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_completion_tokens = request.maxTokens
 
     if (request.reasoningEffort !== undefined) payload.reasoning_effort = request.reasoningEffort
     if (request.verbosity !== undefined) payload.verbosity = request.verbosity
diff --git a/apps/sim/providers/cerebras/index.ts b/apps/sim/providers/cerebras/index.ts
index 3953c6715..c18560048 100644
--- a/apps/sim/providers/cerebras/index.ts
+++ b/apps/sim/providers/cerebras/index.ts
@@ -77,7 +77,7 @@ export const cerebrasProvider: ProviderConfig = {
         messages: allMessages,
       }
       if (request.temperature !== undefined) payload.temperature = request.temperature
-      if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+      if (request.maxTokens != null) payload.max_completion_tokens = request.maxTokens
       if (request.responseFormat) {
         payload.response_format = {
           type: 'json_schema',
diff --git a/apps/sim/providers/deepseek/index.ts b/apps/sim/providers/deepseek/index.ts
index 2aa92b04f..026342498 100644
--- a/apps/sim/providers/deepseek/index.ts
+++ b/apps/sim/providers/deepseek/index.ts
@@ -81,7 +81,7 @@ export const deepseekProvider: ProviderConfig = {
       }
 
       if (request.temperature !== undefined) payload.temperature = request.temperature
-      if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+      if (request.maxTokens != null) payload.max_tokens = request.maxTokens
 
       let preparedTools: ReturnType<typeof prepareToolsWithUsageControl> | null = null
 
diff --git a/apps/sim/providers/gemini/core.ts b/apps/sim/providers/gemini/core.ts
index a7aca1aaa..2dca22e5b 100644
--- a/apps/sim/providers/gemini/core.ts
+++ b/apps/sim/providers/gemini/core.ts
@@ -349,7 +349,7 @@ export async function executeGeminiRequest(
     if (request.temperature !== undefined) {
       geminiConfig.temperature = request.temperature
     }
-    if (request.maxTokens !== undefined) {
+    if (request.maxTokens != null) {
       geminiConfig.maxOutputTokens = request.maxTokens
     }
     if (systemInstruction) {
diff --git a/apps/sim/providers/groq/index.ts b/apps/sim/providers/groq/index.ts
index c5dad01ef..7be9b7386 100644
--- a/apps/sim/providers/groq/index.ts
+++ b/apps/sim/providers/groq/index.ts
@@ -74,7 +74,7 @@ export const groqProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_completion_tokens = request.maxTokens
 
     if (request.responseFormat) {
       payload.response_format = {
diff --git a/apps/sim/providers/mistral/index.ts b/apps/sim/providers/mistral/index.ts
index 736b11c24..f99a3e210 100644
--- a/apps/sim/providers/mistral/index.ts
+++ b/apps/sim/providers/mistral/index.ts
@@ -91,7 +91,7 @@ export const mistralProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_tokens = request.maxTokens
 
     if (request.responseFormat) {
       payload.response_format = {
diff --git a/apps/sim/providers/ollama/index.ts b/apps/sim/providers/ollama/index.ts
index 7b73d1f18..921c1afd0 100644
--- a/apps/sim/providers/ollama/index.ts
+++ b/apps/sim/providers/ollama/index.ts
@@ -105,7 +105,7 @@ export const ollamaProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_tokens = request.maxTokens
 
     if (request.responseFormat) {
       payload.response_format = {
diff --git a/apps/sim/providers/openai/index.ts b/apps/sim/providers/openai/index.ts
index 0d7342fc9..b2cecfceb 100644
--- a/apps/sim/providers/openai/index.ts
+++ b/apps/sim/providers/openai/index.ts
@@ -81,7 +81,7 @@ export const openaiProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_completion_tokens = request.maxTokens
 
     if (request.reasoningEffort !== undefined) payload.reasoning_effort = request.reasoningEffort
     if (request.verbosity !== undefined) payload.verbosity = request.verbosity
diff --git a/apps/sim/providers/openrouter/index.ts b/apps/sim/providers/openrouter/index.ts
index d937e3d0e..bf54a6457 100644
--- a/apps/sim/providers/openrouter/index.ts
+++ b/apps/sim/providers/openrouter/index.ts
@@ -121,7 +121,7 @@ export const openRouterProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_tokens = request.maxTokens
 
     let preparedTools: ReturnType<typeof prepareToolsWithUsageControl> | null = null
     let hasActiveTools = false
diff --git a/apps/sim/providers/vllm/index.ts b/apps/sim/providers/vllm/index.ts
index 4af4ae9d7..0df587264 100644
--- a/apps/sim/providers/vllm/index.ts
+++ b/apps/sim/providers/vllm/index.ts
@@ -135,7 +135,7 @@ export const vllmProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) payload.temperature = request.temperature
-    if (request.maxTokens !== undefined) payload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) payload.max_completion_tokens = request.maxTokens
 
     if (request.responseFormat) {
       payload.response_format = {
diff --git a/apps/sim/providers/xai/index.ts b/apps/sim/providers/xai/index.ts
index 72602ec50..8138265a3 100644
--- a/apps/sim/providers/xai/index.ts
+++ b/apps/sim/providers/xai/index.ts
@@ -92,7 +92,7 @@ export const xAIProvider: ProviderConfig = {
     }
 
     if (request.temperature !== undefined) basePayload.temperature = request.temperature
-    if (request.maxTokens !== undefined) basePayload.max_tokens = request.maxTokens
+    if (request.maxTokens != null) basePayload.max_completion_tokens = request.maxTokens
     let preparedTools: ReturnType<typeof prepareToolsWithUsageControl> | null = null
 
     if (tools?.length) {