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Connections are added inside an Access bundle. At claude.ai/admin-settings/claude-tag, open Access bundles in the left navigation, click into a bundle (or Create one), and go to its Credentials tab.
For a service that doesn’t have a preset Connect button, use Connect another tool on the bundle’s Credentials tab. This works for any service with an HTTP API. The Snowflake and Salesforce guides are worked examples.

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Add a custom HTTP API

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What you need from the service

  • A service-account credential (an API key, token, or OAuth client) — not your personal login
  • The API host (for example api.example.com)
  • How the API authenticates (which header or flow it expects)
See Create a dedicated account per service for the service-account patterns.

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Fill out the Connect another tool form

FieldWhat to enter
NameA label for this connection (for example “Internal billing API”)
Credential typePick the type that matches how the API authenticates; see Credential types
Allowed websitesThe API’s host (for example api.example.com). A wildcard is allowed as the leftmost label. You can’t enter * alone here; a credential is always limited to specific hosts (see Allow all hosts). The credential is sent only to hosts you list here.
Path prefixes (optional)Restrict the credential to specific URL paths under the host. Shown only for the OAuth 2.0 authorization code type.
Custom headersAny extra headers the API requires beyond the credential. Shown only for the Bearer credential type.

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Credential types

TypeUse for
BearerAn API key or token sent as Authorization: Bearer <token>. Most SaaS REST APIs.
BasicHTTP Basic authentication (Authorization: Basic <base64(user:password)>)
Body parameterA token the API expects in the request body or query string instead of a header
AWS SigV4AWS services and APIs that require Signature Version 4 signing
GCP access token (with Service Account Key)Google Cloud APIs; the proxy exchanges the SA key for an access token
GCP IAP (with Service Account Key)Google Cloud services behind Identity-Aware Proxy
OAuth 2.0 JWT bearerAPIs that accept a JWT signed with your private key in exchange for an access token (Salesforce, DocuSign)
OAuth 2.0 client credentialsMachine-to-machine OAuth with a client ID and secret
OAuth 2.0 authorization code (3-legged)OAuth with a user-consent step; the connection stores the resulting refresh token
GitHub AppGitHub repositories; covered separately at Configure GitHub access
If you’re unsure which type, check the service’s API authentication docs for which header or flow it expects.

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AWS SigV4

Use the AWS SigV4 credential type for AWS service APIs (S3, Lambda, Amazon Bedrock, an API Gateway endpoint with IAM authorization). Agent Proxy reads the AWS service and signing region from the hostname and signs each outbound request with the credential at the boundary, so neither the model nor the sandbox holds the keys. The host must be an amazonaws.com endpoint; the proxy can’t sign requests to an API Gateway custom domain or to a non-AWS API that uses Signature Version 4.
FieldValue
Access key IDThe IAM user or role access key, for example AKIAIOSFODNN7EXAMPLE
Secret access keyThe matching secret access key
Session tokenOptional. Only needed for temporary credentials from AWS STS.
Allowed websitesThe AWS service endpoint host, for example s3.us-east-1.amazonaws.com or abc123.execute-api.us-east-1.amazonaws.com
Use long-lived credentials from a dedicated IAM user where you can. Temporary STS credentials work but expire on their own schedule, and the connection stops working when they do; you re-enter all three values to rotate. Claude can call the endpoint with curl, an AWS SDK, or the AWS CLI. The sandbox holds no real AWS credentials, so a CLI or SDK signs the request with placeholder values; Agent Proxy strips that signature and re-signs with the stored credential before the request leaves for AWS. The one shape it can’t re-sign is chunked payload signing. If Claude reports that chunked signing isn’t supported through the proxy, have it set payload_signing_enabled = false in ~/.aws/config and retry.

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When AWS returns SignatureDoesNotMatch

A SignatureDoesNotMatch response from AWS means the request AWS received doesn’t match the one Agent Proxy signed.
CheckWhat to do
The access key ID and secret access key belong to the same IAM identityRe-enter the access key ID, secret access key, and session token together. The form is write-only, so a partial update can leave them mismatched.
No proxy or gateway of your own sits between Anthropic and AWSA second proxy that adds, strips, or reorders headers, or that re-signs the request, invalidates the signature Agent Proxy attached. Point Allowed websites at the AWS endpoint directly.
A dropped or expired session token is a different failure: AWS rejects it with a token error such as InvalidClientTokenId, not SignatureDoesNotMatch. Rotate all three fields.

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Add a custom MCP server

To give Claude an MCP server (one you run, or a vendor’s hosted MCP endpoint), the pattern is a plugin plus a credential:
1

Add a plugin that declares the MCP server

In the bundle’s Plugins tab (or via your skills repository), add a plugin whose .mcp.json points at the server URL. The plugin tells Claude the server exists and how to call it.
2

Add a credential for the server's host

On the Credentials tab, click Connect another tool and add a credential for the MCP server’s host (for example, a Bearer token with Allowed websites set to your-mcp-host.example.com). This lets the call leave the sandbox with auth attached.
The plugin’s .mcp.json is loaded because it’s part of an attached plugin; an .mcp.json checked into a repository Claude clones is not loaded.

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Verify the connection

In a channel under the bundle’s scope, in a new thread, ask Claude to make a small read against the API: 
@Claude can you reach api.example.com? Try a GET on /health.
Check the service’s own audit log to confirm the call landed under your service account.