MCP Endpoints Bug Fixes

Issues Fixed

1. create_task - Missing created_by Field

Problem:

{"error": "pq: null value in column "created_by" of relation "tasks" violates not-null constraint"}

Root Cause: The tasks table has a NOT NULL constraint on the created_by column, but the MCP handler's executeCreateTask function wasn't including this field in the INSERT statement.

Solution:

• Added created_by parameter support to the create_task tool
• If created_by is not provided, the function now automatically queries the first agent from the project
• Updated the INSERT statement to include the created_by field
• Updated the tool schema to document the created_by parameter

Changes Made:

// Now accepts created_by parameter
createdBy, _ := args["created_by"].(string)

// Auto-assign first agent if not provided
if createdBy == "" {
    err := h.db.QueryRow(`SELECT id FROM agents WHERE project_id = $1 LIMIT 1`, projectID).Scan(&createdBy)
    if err != nil {
        return `{"error": "created_by is required or no agents found in project"}`, true
    }
}

// Include created_by in INSERT
query := `INSERT INTO tasks (id, project_id, title, description, status, priority, created_by, assigned_to) 
          VALUES ($1, $2, $3, $4, 'pending', $5, $6, $7) RETURNING id, created_at`

2. add_context - Malformed Array Literal for Tags

Problem:

{"error": "pq: malformed array literal: "["documentation","backend","onboarding"]""}

Root Cause: The executeAddContext function was converting tags to JSON format using json.Marshal(), but PostgreSQL's TEXT[] column type expects PostgreSQL array literals, not JSON arrays. The difference:

• JSON format: ["tag1","tag2"]
• PostgreSQL array format: {tag1,tag2}

Solution:

• Added missing agent_id requirement (contexts table requires this field)
• If agent_id is not provided, automatically query the first agent from the project
• Use pq.Array() from the github.com/lib/pq package for proper PostgreSQL array handling
• Added import for "github.com/lib/pq" package

Changes Made:

// Import added
import "github.com/lib/pq"

// Handle agent_id requirement
agentID, _ := args["agent_id"].(string)

if agentID == "" {
    err := h.db.QueryRow(`SELECT id FROM agents WHERE project_id = $1 LIMIT 1`, projectID).Scan(&agentID)
    if err != nil {
        return `{"error": "agent_id is required or no agents found in project"}`, true
    }
}

// Convert tags properly for PostgreSQL
var tags []string
if tagsInterface, ok := args["tags"].([]interface{}); ok {
    for _, tag := range tagsInterface {
        if tagStr, ok := tag.(string); ok {
            tags = append(tags, tagStr)
        }
    }
}

// Use pq.Array for proper PostgreSQL array handling
err := h.db.QueryRow(query, id, projectID, agentID, title, content, pq.Array(tags)).Scan(&createdAt)

Testing the Fixes

Test create_task:

With created_by (explicit):

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "create_task",
    "arguments": {
      "project_id": "your-project-id",
      "title": "Test Task",
      "description": "Testing create_task fix",
      "priority": "medium",
      "created_by": "agent-id"
    }
  }
}

Without created_by (auto-assigned):

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "tools/call",
  "params": {
    "name": "create_task",
    "arguments": {
      "project_id": "your-project-id",
      "title": "Test Task",
      "description": "Testing auto-assign",
      "priority": "high"
    }
  }
}

Test add_context:

With agent_id (explicit):

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "add_context",
    "arguments": {
      "project_id": "your-project-id",
      "agent_id": "agent-id",
      "title": "Testing Documentation",
      "content": "This is a test context with proper array handling",
      "tags": ["documentation", "backend", "testing"]
    }
  }
}

Without agent_id (auto-assigned):

{
  "jsonrpc": "2.0",
  "id": 2,
  "method": "tools/call",
  "params": {
    "name": "add_context",
    "arguments": {
      "project_id": "your-project-id",
      "title": "Auto-assigned Context",
      "content": "Testing automatic agent assignment",
      "tags": ["test", "fix"]
    }
  }
}

Files Modified

1. internal/mcp/handler.go

   • Added pq package import
   • Fixed executeCreateTask() to handle created_by field
   • Fixed executeAddContext() to use proper PostgreSQL array format and handle agent_id field
   • Updated tool schemas to document the new optional parameters

2. cmd/server/main.go (previous fix)

   • Added CORS headers to health endpoint

Summary

Both issues have been resolved:

• ✅ create_task now properly handles the created_by constraint
• ✅ add_context now properly handles PostgreSQL array format for tags
• ✅ Both functions automatically assign the first project agent if not explicitly provided
• ✅ Tool schemas updated to reflect the changes

The server has been successfully rebuilt and is ready for testing.