MCP server returns "Access denied" from Relevance AI despite valid API key

TL;DR

For "Access denied to MCP server at https://connect.composio.dev/mcp. Please check your authentication credentials.": check your version of Composio first , maintainers often fix the underlying bug in a later release, and the thread may predate it.

Access denied to MCP server at https://connect.composio.dev/mcp. Please check your authentication credentials.

When to use

You are seeing this: Issue ComposioHQ/composio#3507 (closed, 9 comments): Hi Composio team, I'm a beginner AI student and I'm having an issue connecting to Composio's MCP server from Relevance AI. Use this skill when you run into "MCP server returns "Access denied" from Relevance AI despite valid API key".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

What happened

Issue ComposioHQ/composio#3507 (closed, 9 comments): Hi Composio team, I'm a beginner AI student and I'm having an issue connecting to Composio's MCP server from Relevance AI. Error: "Access denied to MCP server at https://connect.composio.dev/mcp. Please check your authentication credentials." What I tried: - With header x-consumer-api-key + my API key → Access denied - Without any headers (as suggested by your chatbot) → Same error My setup: - Client: Relevance AI → "Connect my own MCP" - MCP URL: https://connect.composio.dev/mcp - API key - taken from Install → MCP URL page in my Composio Connect dashboard (created June 1,...

What works

This 'Access denied' from connect.composio.dev/mcp was a Composio-side problem in May and was fixed in early June; both auth methods were tested working afterward: the x-consumer-api-key header with the consumer key from the Install page of the Composio Connect dashboard (called AI Clients in older versions), and the OAuth flow with no header. If it resurfaces, the maintainer asked for an email with a link to the issue and the client you're using, since it's a server-side thing rather than something wrong with your key.

Caveats

This comes from one real issue thread (https://github.com/ComposioHQ/composio/issues/3507); it is the verified fix or approach from that thread, not a general manual. Check your version of Composio first , maintainers often fix the underlying bug in a later release, and the thread may predate it.

Issue gh:ComposioHQ/composio#3507 asked: Issue ComposioHQ/composio#3507 (closed, 9 comments): Hi Composio team, I'm a beginner AI student and I'm having an issue connecting to Composio's MCP server from Relevance AI. Error: "Access denied to MCP server at https://connect.composio.dev/mcp. Please check your authentication credentials." What I tried: - With header x-consumer-api-key + my API key → Access denied - Without any headers (as suggested by your chatbot) → Same error My setup: - Client: Relevance AI → "Connect my own MCP" - MCP URL: https://connect.composio.dev/mcp - API key - taken from Install → MCP URL page in my Composio Connect dashboard (created June 1,... The verified answer from the thread: This 'Access denied' from connect.composio.dev/mcp was a Composio-side problem in May and was fixed in early June; both auth methods were tested working afterward: the x-consumer-api-key header with the consumer key from the Install page of the Composio Connect dashboard (called AI Clients in older versions), and the OAuth flow with no header. If it resurfaces, the maintainer asked for an email with a link to the issue and the client you're using, since it's a server-side thing rather than something wrong with your key. Source: https://github.com/ComposioHQ/composio/issues/3507