MCP Inspector OAuth: how to use a manually entered client ID instead of dynamic client registration?
In the MCP Inspector guided OAuth flow, the tool always assumes dynamic client registration (DCR), which is a problem for providers like AWS Cognito that do not support DCR out of the box. The MCP spec allows clients to hardcode a client ID or let the user enter one. Does Inspector support entering an existing client ID or client secret manually? This was reported on 2025-08-05 against modelcontextprotocol/inspector and closed on 2026-01-18.
Originally asked on GitHub: https://github.com/modelcontextprotocol/inspector/issues/683
5 answers
Closed as completed: on 2026-01-18 a maintainer said the issue 'should be fixed by PR #684' and closed it, asking users to reopen if the problem persists. The thread does not state whether the PR was merged or verified.
Per the contributor of PR #684 (comment on 2025-08-06), the change makes the guided OAuth flow use a manually entered client ID instead of always assuming dynamic client registration, which addresses the deviation from the MCP spec. Only a client ID is supported: no client secret, because MCP Inspector is designed to act as a public client. Adding client secret support and token exchange for confidential clients would require a larger PR.
This means providers that require confidential-client credentials (client secret plus token exchange) are not covered by this fix. The thread also links issue #575, which requests support for initial access tokens for DCR, but it does not say whether that issue was addressed.
If you update Inspector to a build containing PR #684 and the guided OAuth flow still forces dynamic registration, the maintainer asked you to reopen the issue.
Did this work for you?What @2underscores tried on GitHub (Outcome unclear)
A contributor implemented PR #684 so the guided OAuth flow uses a manually entered client ID instead of always assuming dynamic client registration. No client secret was added because Inspector acts as a public client.
Did this work for you?What @olaservo tried on GitHub (Outcome unclear)
A maintainer closed the issue as completed, stating it should be fixed by PR #684, and asked users to reopen if the problem still occurred.
Did this work for you?What a GitHub user tried on GitHub (Outcome unclear)
The reporter requested an option in the guided OAuth flow to enter a client ID and client secret manually, citing the MCP spec's allowance for providers that do not support dynamic client registration.
Source: https://github.com/modelcontextprotocol/inspector/issues/683 (opens external site)
Did this work for you?What @franz-zuplo tried on GitHub (Outcome unclear)
A commenter agreed that mandatory DCR increases testing overhead, noting AWS Cognito does not support DCR out of the box.
Did this work for you?
Related questions
- MCP Inspector 0.10.2 sends null for unset optional params (error -32602)?
- Why does npx @modelcontextprotocol/inspector fail with 'mcp-inspector: command not found' after 0.10.0?
- How do I increase MCP Inspector's 10-second request timeout?
- MCP Inspector crashes with 'Controller is already closed' on fastmcp Streamable HTTP
- Why does the MCP Inspector Docker container refuse connections on localhost:6274, and how do I fix it?