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Most providers use OAuth. Some of them (GitHub, Google, Microsoft Entra, and others) ask you to register an application before you can connect. During registration they ask for a redirect URI, also called a callback URL. Use this one:

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What a callback URL is

When you connect an integration, you sign in on the provider’s own website, not on Cominty. The provider never shares your password with Cominty. Instead, once you approve the access, it sends your browser back to a web address that you registered in advance. That address is the callback URL. The provider adds a short-lived code to the address when it redirects you. Cominty receives that code at the callback URL and trades it for an access token. The token is what lets agents call the provider’s tools. The provider only redirects to addresses it already knows. That is why it asks you to register the callback URL first: it prevents anyone else from receiving the code.

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When you need one

You need the callback URL when a provider asks you to register your own OAuth app. You paste the URL into the app’s form, and the provider gives you a client ID and a client secret in return. Each provider has its own steps. For Google BigQuery, see the BigQuery guide.

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How it fits in the flow

  1. You click Authorize. Your browser goes to the provider.
  2. You sign in with the provider and approve the access.
  3. The provider redirects your browser to the callback URL, with a code.
  4. The MCP hub trades the code, together with your client secret, for a token.
  5. Cominty stores the token. From then on, agents call the provider’s tools with it, and you never repeat steps 1 to 4 unless the token is revoked.
The callback URL only matters at step 3. If it does not match what you registered, the provider stops the flow there.

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Rules

  • Paste the URL exactly as shown. Providers compare it character by character.
  • Keep https and do not add a trailing slash.
  • Register it as a redirect URI, not as a webhook or homepage URL.
  • Use the same URL for every integration.

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After registering

The provider gives you a client ID and a client secret. Add both to the integration in Cominty. Treat the secret like a password. If it leaks, rotate it at the provider.

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Troubleshooting

Does the provider restrict access by IP? Allowlist the MCP hub address listed on the Static IP addresses page.
Registering the wrong callback URL is the most common cause of a redirect_uri_mismatch error. Check the URL first when authorization fails.