bug: Anthropic: "invalid x-api-key" with parse_prd Despite Valid Key

[C-broderick-225]

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Description

The Task Master MCP tool parse_prd consistently fails with an "invalid x-api-key" error when using an Anthropic model and API key, despite several indicators suggesting the key and configuration should be valid. The same Anthropic API key, when used for direct API calls (e.g., via curl in PowerShell), functions correctly. This suggests an issue within Task Master or its interaction with the Anthropic API via the MCP server, specifically for operations like parse_prd.

Steps to Reproduce

1. Initial Setup:
   • Ensure the corresponding ANTHROPIC_API_KEY is set in the env block of .cursor/mcp.json.
   • Original .cursor/mcp.json env block looked similar to this before cleanup (API keys redacted for brevity but were present):

        ```json
        "env": {
            "ANTHROPIC_API_KEY": "...",
            "PERPLEXITY_API_KEY": "...",
            "OPENROUTER_API_KEY": "...",
            "MODEL": "claude-3-7-sonnet-20250219", // Example, actual might vary
            "PERPLEXITY_MODEL": "sonar-pro",       // Example
            "MAX_TOKENS": 64000,
            "TEMPERATURE": 0.2,
            "DEFAULT_SUBTASKS": 5,
            "DEFAULT_PRIORITY": "medium"
        }

2. Verify Model and Key Status:

   • Run the mcp_taskmaster-ai_models tool.
   • Observe that the main model is set to the Anthropic model and keyStatus for mcp is true.
   • Example output snippet:

     {
       "activeModels": {
         "main": {
           "provider": "anthropic",
           "modelId": "claude-3-7-sonnet-20250219",
           "keyStatus": { "cli": true, "mcp": true }
         }
       }
     }

3. Attempt to Parse PRD:

   • Ensure a PRD file exists (e.g., scripts/gallery_project_prd.txt).
   • Run the mcp_taskmaster-ai_parse_prd tool:

     mcp_taskmaster-ai_parse_prd(force = True, input = "scripts/gallery_project_prd.txt", projectRoot = "your/project/root")
     

4. Verify API Key Externally (Optional but Recommended):

   • Using the exact same Anthropic API key (..."), make a direct API call to an Anthropic model endpoint using a tool like curl` in PowerShell.
   • Observe that this direct call is successful.

5. Restart MCP Server:

   • Restart the taskmaster-ai MCP server through the IDE interface.
   • Retry step 3.

Expected Behavior

The mcp_taskmaster-ai_parse_prd command should successfully parse the PRD file using the configured Anthropic model and API key, generating tasks without any API key errors.

Actual Behavior

The mcp_taskmaster-ai_parse_prd command consistently fails with the following error:

Tool: parse_prd, Result: Error: invalid x-api-key

This occurs even after:

• Confirming the Anthropic key is reported as active for MCP by mcp_taskmaster-ai_models.
• Cleaning the .cursor/mcp.json file.
• Restarting the MCP server.
• Replacing the Anthropic API key with a new one (which also tested valid with mcp_taskmaster-ai_models and direct curl calls).

Logs

Error message from mcp_taskmaster-ai_parse_prd:

{"mcp_taskmaster-ai_parse_prd_response": {"results": ["Tool: parse_prd, Result: Error: invalid x-api-key"]}}

Output from mcp_taskmaster-ai_models showing key as active:

{
  "data": {
    "activeModels": {
      "main": {
        "provider": "anthropic",
        "modelId": "claude-3-7-sonnet-20250219",
        "sweScore": 0.49,
        "cost": { "input": 3, "output": 15 },
        "keyStatus": { "cli": true, "mcp": true }
      },
      // ... other models ...
    },
    "message": "Successfully retrieved current model configuration"
  }
}

Environment

• Task Master version: [Please specify Task Master version if known, e.g., from 'npx task-master-ai --version']
• Node.js version: [Please specify Node.js version, e.g., from 'node --version']
• Operating system: Windows 10 (win32 10.0.26100)
• IDE (if applicable): Cursor

Additional Context

The core issue is the discrepancy: Task Master's models tool reports the Anthropic API key as valid for MCP, and direct API calls using the same key (via curl) work. However, more complex MCP operations like parse_prd that use this key and model fail with an "invalid x-api-key" error. This suggests the problem might be in how Task Master handles or transmits the API key for certain types of requests to Anthropic, or how it interprets the response from Anthropic's API during these specific operations. The issue has been persistent across different Anthropic API keys and MCP server restarts.

[stefanraath3]

ive experienced this error before, the inflight package that taskmaster uses needs the latest node lts, so it resolved when i upgraded node using nvm. also i always install tm locally not globally as that sometimes has unintended consequences.

[Crunchyman-ralph]

any chance I can see the whole mcp.json by redacting the env vars ?

[Crunchyman-ralph]

We seem to be compatible with node 23, and 14 as well. anything under that we aren't compatible with.

Let me know what else you've tried, I'm unable to reproduce, so I'm moving this to discussions see if its a one-off thing