Workaround
Authenticate via the MCP OAuth flow (client registration, authorization code + PKCE, token exchange) and send the issued MCP access token as the Bearer token to /mcp.
The error
401 UnauthorizedReported in freee/freee-mcp issue #471: “https://mcp.freee.co.jp/mcp に freee Public API の access_token を使うと 401 Unauthorized になる”.
What fixed it
大まかな流れとしては、client registration / authorization code + PKCE / token exchange を行い、`https://mcp.freee.co.jp/token` で発行された MCP 用 access token を `Authorization: Bearer ...` として `/mcp` に送る形になります。
— a maintainer's comment on the issue (Japanese, quoted as written).
Source and dates
| Repository | freee/freee-mcp |
|---|---|
| Issue | https://mcp.freee.co.jp/mcp に freee Public API の access_token を使うと 401 Unauthorized になる |
| Evidence | a maintainer's comment |
| Status | Workaround (a way around it, given in the evidence) |
| Fixed in | No version is named |
| Issue closed | 2026-05-25 |
| Read from GitHub | 2026-11-07 |
| Approved by a person | 2026-11-07 |
This page records what the vendor's own GitHub repository says. The error text, the issue title and the quote are copied as written; the summary at the top is one sentence limited to the quote, and a person approved this fact on 2026-11-07. KanseiLink has not re-run the fix. Read the issue before applying it. Something changed? Write to contact@synapse-arrows.com.
For AI agents
The same fact is returned as issue_facts by lookup({ service_id: 'freee' }) on the KanseiLink MCP server (https://mcp.kansei-link.com/mcp), next to the other checked facts for freee. Connection guide: freee service page.
Other freee MCP errors
- freee MCP: "401 company_not_found" — the fix from the official GitHub issue
- freee MCP: "Couldn't reach the MCP server. You can check the server URL and verify the server is…" — the fix from the official GitHub issue
- freee MCP: "MCP error -32602: Input validation error: Invalid arguments for tool freee_api_put: [" — fixed in v0.26.4
- freee MCP: "Starting OAuth flow..." — the fix from the official GitHub issue