MCP server startup error: Invalid schema for tool initialize_project (JSON Schema Draft 2020-12 not supported) #29

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opened 2025-10-14 15:38:49 -06:00 by navan · 0 comments

navan commented

2025-10-14 15:38:49 -06:00

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Originally created by @almai on 10/8/2025

Bug Description

The Taskmaster AI MCP server fails to start in Augment IDE (WebStorm) with the following error:

⚠️  MCP server startup error: Invalid schema for tool initialize_project: no schema with key or ref "https://json-schema.org/draft/2020-12/schema" 
   Command: npx -y --package=task-master-ai task-master-ai

Environment

Task Master version: 0.28.0 (latest)
MCP Client: Augment IDE (WebStorm 2025.2)
Node.js: v22.20.0
OS: macOS (darwin)

Root Cause

The initialize_project tool is using JSON Schema Draft 2020-12 (https://json-schema.org/draft/2020-12/schema), but the MCP client only supports older JSON Schema drafts (likely Draft-07 or Draft-04).

Impact

❌ MCP server fails to start in Augment IDE
❌ All Taskmaster AI MCP tools unavailable
✅ CLI works fine (task-master command)

Expected Behavior

The MCP server should use a JSON Schema draft version that's compatible with common MCP clients (Draft-07 or Draft-04).

Actual Behavior

MCP server fails to initialize due to unsupported JSON Schema version.

Workaround

None currently available. Users must use the CLI instead of MCP integration.

Suggested Fix

Downgrade the JSON Schema version used in the initialize_project tool definition from Draft 2020-12 to Draft-07 or Draft-04.

MCP Specification: https://modelcontextprotocol.io/
JSON Schema Draft-07: https://json-schema.org/draft-07/schema
JSON Schema Draft 2020-12: https://json-schema.org/draft/2020-12/schema

Additional Context

This issue was discovered when trying to use Taskmaster AI MCP server with Augment IDE. The CLI works perfectly, but the MCP integration fails immediately on startup.

The error appears in the Augment IDE output when trying to connect to the MCP server configured in ~/.augment/settings.json.

*Originally created by @almai on 10/8/2025* ## Bug Description The Taskmaster AI MCP server fails to start in Augment IDE (WebStorm) with the following error: ``` ⚠️ MCP server startup error: Invalid schema for tool initialize_project: no schema with key or ref "https://json-schema.org/draft/2020-12/schema" Command: npx -y --package=task-master-ai task-master-ai ``` ## Environment - **Task Master version**: 0.28.0 (latest) - **MCP Client**: Augment IDE (WebStorm 2025.2) - **Node.js**: v22.20.0 - **OS**: macOS (darwin) ## Root Cause The `initialize_project` tool is using **JSON Schema Draft 2020-12** (`https://json-schema.org/draft/2020-12/schema`), but the MCP client only supports older JSON Schema drafts (likely Draft-07 or Draft-04). ## Impact - ❌ MCP server fails to start in Augment IDE - ❌ All Taskmaster AI MCP tools unavailable - ✅ CLI works fine (`task-master` command) ## Expected Behavior The MCP server should use a JSON Schema draft version that's compatible with common MCP clients (Draft-07 or Draft-04). ## Actual Behavior MCP server fails to initialize due to unsupported JSON Schema version. ## Workaround None currently available. Users must use the CLI instead of MCP integration. ## Suggested Fix Downgrade the JSON Schema version used in the `initialize_project` tool definition from Draft 2020-12 to Draft-07 or Draft-04. ## Related Information - MCP Specification: https://modelcontextprotocol.io/ - JSON Schema Draft-07: https://json-schema.org/draft-07/schema - JSON Schema Draft 2020-12: https://json-schema.org/draft/2020-12/schema ## Additional Context This issue was discovered when trying to use Taskmaster AI MCP server with Augment IDE. The CLI works perfectly, but the MCP integration fails immediately on startup. The error appears in the Augment IDE output when trying to connect to the MCP server configured in `~/.augment/settings.json`.