fix: defensive JSON.parse for stringified object/array params (#605) (#606)

* chore: update n8n to 2.8.3 and bump version to 2.35.3

- Updated n8n from 2.6.3 to 2.8.3
- Updated n8n-core from 2.6.1 to 2.8.1
- Updated n8n-workflow from 2.6.0 to 2.8.0
- Updated @n8n/n8n-nodes-langchain from 2.6.2 to 2.8.1
- Fixed node loader to bypass restricted package.json exports in
  @n8n/n8n-nodes-langchain >=2.9.0 (resolves via absolute paths)
- Fixed community doc generator for cloud LLMs: added API key env var
  support, switched to max_completion_tokens, auto-omit temperature
- Rebuilt node database with 1,236 nodes (673 n8n-nodes-base,
  133 @n8n/n8n-nodes-langchain, 430 community)
- Refreshed community nodes (361 verified + 69 npm) with 424 AI summaries
- Updated README badge with new n8n version and node counts
- Updated CHANGELOG with dependency changes

Conceived by Romuald Członkowski - https://www.aiadvisors.pl/en

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: update documentation-generator tests for max_completion_tokens

- Updated test assertions from max_tokens to max_completion_tokens
- Updated testConnection token limit expectation from 10 to 200
- Added temperature to test config to match new configurable behavior

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix: defensive JSON.parse for stringified object/array params (#605)

Claude Desktop 1.1.3189 serializes object/array MCP parameters as JSON
strings, causing ZodError failures for ~60% of tools. Add schema-driven
coercion in the central CallToolRequestSchema handler to detect and parse
them back automatically.

Conceived by Romuald Czlonkowski - https://www.aiadvisors.pl/en

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

src/mcp/server.ts

@@ -720,7 +720,12 @@ export class N8NDocumentationMCPServer {
           });
         }
       }
-      
+
+      // Workaround for Claude Desktop 1.1.3189 string serialization bug.
+      // The MCP client serializes object/array parameters as JSON strings.
+      // Use the tool's inputSchema to detect and parse them back.
+      processedArgs = this.coerceStringifiedJsonParams(name, processedArgs);
+
       try {
         logger.debug(`Executing tool: ${name}`, { args: processedArgs });
         const startTime = Date.now();
@@ -1125,6 +1130,50 @@ export class N8NDocumentationMCPServer {
     return true;
   }
 
+  /**
+   * Coerce stringified JSON parameters back to objects/arrays.
+   * Workaround for Claude Desktop 1.1.3189 which serializes object/array
+   * params as JSON strings before sending them to MCP servers.
+   */
+  private coerceStringifiedJsonParams(
+    toolName: string,
+    args: Record<string, any> | undefined
+  ): Record<string, any> | undefined {
+    if (!args || typeof args !== 'object') return args;
+
+    const allTools = [...n8nDocumentationToolsFinal, ...n8nManagementTools];
+    const tool = allTools.find(t => t.name === toolName);
+    if (!tool?.inputSchema?.properties) return args;
+
+    const properties = tool.inputSchema.properties;
+    const coerced = { ...args };
+
+    for (const [key, value] of Object.entries(coerced)) {
+      if (typeof value !== 'string') continue;
+      const expectedType = (properties as any)[key]?.type;
+      if (expectedType !== 'object' && expectedType !== 'array') continue;
+
+      const trimmed = value.trim();
+      const validPrefix = (expectedType === 'object' && trimmed.startsWith('{'))
+                       || (expectedType === 'array'  && trimmed.startsWith('['));
+      if (!validPrefix) continue;
+
+      try {
+        const parsed = JSON.parse(trimmed);
+        const isArray = Array.isArray(parsed);
+        if ((expectedType === 'object' && typeof parsed === 'object' && !isArray)
+         || (expectedType === 'array'  && isArray)) {
+          coerced[key] = parsed;
+          logger.warn(`Coerced stringified ${expectedType} param "${key}" for tool "${toolName}"`);
+        }
+      } catch {
+        // Not valid JSON — keep original string, downstream validation will report the error
+      }
+    }
+
+    return coerced;
+  }
+
   async executeTool(name: string, args: any): Promise<any> {
     // Ensure args is an object and validate it
     args = args || {};