Notion MCP Bug

[Django-Jiang]

🐛 Bug Description

I continuously got api issue when test on Notion MCP

and I note that current configed notion MCP version is '2022-06-08', not sure if it is related to notion api upgrade

We’ve released Notion API version 2025‑09‑03, introducing first-class support for multi-source databases. This enables a single database to contain multiple linked data sources — unlocking powerful new workflows.

For more information about data sources, see [our FAQs.](https://developers.notion.com/docs/upgrade-faqs-2025-09-03)

However, this change is not backwards-compatible. Most existing database integrations must be updated to prevent disruptions.

❗️
Code changes required

If your integration is still using a previous API version and a user adds another data source to a database, the following API actions will fail:

Create page when using the database as the parent
Database read, write, or query
Writing relation properties that point to that database

📷 Recurrence Steps

No response

🚦 Expected Behavior

No response

📝 Additional Information

No response

[xyliugo]

Hi, sorry for the late response, we have been busy with some other issues recently. We have tested that using the old version of the Notion API does not affect the evaluation of this benchmark, since the new version mainly relates to the newly introduced concept of data source. We will consider adapting our tasks to the new version of the Notion API if needed. Thanks for pointing it out, it’s a good catch.

[Django-Jiang]

I tried claude-4-sonnet on Notion, and got all 0 pass rate due to API error. And I checked the log, initial few tool calls are fine but later some writing calls failed, so I wonder if the team check this setup.

[xyliugo]

1. "Writing calls failed" is fairly normal; sometimes the model produces incorrect tool call arguments (but the agent can retry).
2. Regarding the "0 pass rate", it's possible that something went wrong with the initial state setup. We have tested the Notion API many times, and neither we nor others have encountered the issue you mentioned. So we guess the environment setup might be a bit problematic?

Could you please share some complete trajectories? we can help check them.

[xingyuHuxingyu]

I’ve encountered similar issues with Notion—it appears the MCP service isn’t fully compatible with the current Notion API. As a result, none of the tasks have been completed.
This seems to be a systemic issue rather than a problem with the agent itself.(gpt-5)
For reference, I’ve shared one trajectory for the task: python_roadmap__expert_level_lessons.
You can check it~
execution.log

and here is an analysis:
**API-post-page Functional Analysis *

---

1. What API-post-page Does

API-post-page is a Notion API utility for creating pages. Its core responsibilities are:

Primary Functions

• Create new pages inside a Notion workspace.
• Support multiple parent types:
  – page_id → create a sub-page under an existing page.
  – database_id → create a new record (row) inside a database.

Role inside MCPMark (inferred from execution logs):

API-post-page({
    "parent": {"database_id": "2c65d1cf-e7c4-81d4-983c-efa8ecea8d21"},  # Chapters DB
    "properties": {"Name": {"title": [{"text": {"content": "Expert Level"}}]}},
    "icon": {"type": "emoji", "emoji": "🟣"}
})

---

2. Is It Mandatory?

For this task: YES, absolutely.

Why it is non-negotiable
Required operations:

1. Insert a “Expert Level” row into the Chapters database.
2. Insert three new course rows into the Steps database.
3. Wire up parent/child relations and chapter references.

No viable substitutes
❌ API-patch-block-children – can only append blocks, not database rows.
❌ API-create-a-comment – creates comments, not pages.
❌ API-update-a-database – edits schema, not data.

Notion data model recap

Workspace
├── Page
├── Database
    ├── Row 1  (Page inside DB)
    ├── Row 2  ← needs API-post-page
    └── Row 3

---

3. Root Cause of the Current Failure

Schema defect in the MCP server

// Current (buggy) implementation
"parent": {
  "required": ["page_id"],        // only sub-page creation accepted
  "additionalProperties": true    // claims extensibility, but breaks
}

// Required by official Notion API
"parent": {
  "database_id": "xxx"            // mandatory for DB rows
}

Evidence from logs

API-post-page {"parent": {"database_id": "..."}, "properties": {...}}
→ Error: body.parent should be an object, instead was "{\"database_id\":...}"

---

4. Way Forward

Short-term (no API fix)

• The agent cannot finish the task; it lacks the ability to create database rows.
• Best fallback: document the spec with API-patch-block-children.

Long-term (fix the API)

• Repair the API-post-page schema in the MCP server.
• Accept the full Notion API payload, including database_id.
• Validate that rows are created successfully.

Conclusion: API-post-page is indispensable for any task that requires inserting new database rows in Notion. The present blockage is a server-side implementation flaw, rendering the agent unable to complete such tasks.

[xyliugo]

I’ve encountered similar issues with Notion—it appears the MCP service isn’t fully compatible with the current Notion API. As a result, none of the tasks have been completed. This seems to be a systemic issue rather than a problem with the agent itself.(gpt-5) For reference, I’ve shared one trajectory for the task: python_roadmap__expert_level_lessons. You can check it~ execution.log

and here is an analysis: **API-post-page Functional Analysis *

1. What API-post-page Does

API-post-page is a Notion API utility for creating pages. Its core responsibilities are:

Primary Functions

• Create new pages inside a Notion workspace.
• Support multiple parent types:
  – page_id → create a sub-page under an existing page.
  – database_id → create a new record (row) inside a database.

Role inside MCPMark (inferred from execution logs):

API-post-page({
"parent": {"database_id": "2c65d1cf-e7c4-81d4-983c-efa8ecea8d21"}, # Chapters DB
"properties": {"Name": {"title": [{"text": {"content": "Expert Level"}}]}},
"icon": {"type": "emoji", "emoji": "🟣"}
})

2. Is It Mandatory?

For this task: YES, absolutely.

Why it is non-negotiable Required operations:

1. Insert a “Expert Level” row into the Chapters database.
2. Insert three new course rows into the Steps database.
3. Wire up parent/child relations and chapter references.

No viable substitutes ❌ API-patch-block-children – can only append blocks, not database rows. ❌ API-create-a-comment – creates comments, not pages. ❌ API-update-a-database – edits schema, not data.

Notion data model recap

Workspace
├── Page
├── Database
    ├── Row 1  (Page inside DB)
    ├── Row 2  ← needs API-post-page
    └── Row 3

3. Root Cause of the Current Failure

Schema defect in the MCP server

// Current (buggy) implementation
"parent": {
"required": ["page_id"], // only sub-page creation accepted
"additionalProperties": true // claims extensibility, but breaks
}

// Required by official Notion API
"parent": {
"database_id": "xxx" // mandatory for DB rows
}
Evidence from logs

API-post-page {"parent": {"database_id": "..."}, "properties": {...}}
→ Error: body.parent should be an object, instead was "{\"database_id\":...}"

4. Way Forward

Short-term (no API fix)

• The agent cannot finish the task; it lacks the ability to create database rows.
• Best fallback: document the spec with API-patch-block-children.

Long-term (fix the API)

• Repair the API-post-page schema in the MCP server.
• Accept the full Notion API payload, including database_id.
• Validate that rows are created successfully.

Conclusion: API-post-page is indispensable for any task that requires inserting new database rows in Notion. The present blockage is a server-side implementation flaw, rendering the agent unable to complete such tasks.

Thanks for reporting this. After investigation, we believe the root cause is a schema mismatch from the Notion MCP server, not an issue with the agent logic itself.

Specifically, the list_tools output provided by @notionhq/notion-mcp-server exposes overly restrictive and partially incorrect JSON Schemas (for example around API-post-page, database parents, and page properties), which do not fully reflect the actual Notion API behavior. This can lead models to mis-handle inputs (for example unnecessary stringification or assuming certain operations are unsupported), even though the underlying API call would succeed.

We have also confirmed that other users in the community have encountered similar schema-related issues with the Notion MCP tools, particularly around page creation and database property updates (https://discuss.ai.google.dev/t/notion-mcp-tool-failures-validation-error-on-property-keys-api-patch-page-schema-mismatch/109381?utm_source=chatgpt.com).

We are planning to address this by widening / correcting the tool schemas on the client side to better align with the real Notion API semantics. A fix will be applied in a future update.

Thanks again for the detailed logs, they were helpful in isolating this.