Retell AI
Connect Retell AI to place and monitor voice and chat calls, build AI agents, and read transcripts, recordings, and analysis.
One workspace API key, created under Settings > API Keys in the Retell dashboard, pasted into PopMCP's single API key field and sent as an Authorization: Bearer header.
- Setup time
- 3 min
- Auth
- API credentials
- API base URL
- https://api.retellai.com
- Rate limits
- Retell publishes no REST request-per-second cap. The limits that bite are per workspace: concurrency, which defaults to 20 simultaneous calls on Pay-As-You-Go, and CPS, the rate at which new calls can start, set per telephony path. Both are adjustable on the Settings > Limits page.
Before you begin
- A Retell AI account with at least one workspace at dashboard.retellai.com
- Admin or Developer access to that workspace, because API keys are issued per workspace
- The workspace that owns the agents, phone numbers and call history PopMCP should read
Get your credentials
Sign in and pick the workspace
Open dashboard.retellai.com and sign in. Use the workspace switcher in the top-left corner to select the workspace that owns the agents and phone numbers PopMCP should reach.
Open Settings, then the API Keys tab
Click Settings in the sidebar under System, then open the API Keys tab. Leave the key flagged Set as Webhook Key alone and create a separate one for PopMCP.
API Keys
Keys authenticate REST requests for this workspace only.
| Name | Key | Permissions | Webhook | Created |
|---|---|---|---|---|
| DefaultAuto-generated | key_****11ab | Full access | Webhook key | Jan 12, 2026 |
| ZapierRestricted | key_****7d40 | History: Read | Mar 4, 2026 |
The auto-generated webhook key cannot be deleted.
Add a key named PopMCP
Click Add, type PopMCP in the Name field, and click Create. Leave Restrict permissions switched off so the key keeps full access.
API Keys
| Group | Permission | No Access | Read | Edit |
|---|---|---|---|---|
| Build | Agent | x | ||
| Build | Testing | x | ||
| Monitor | History | x | ||
| Monitor | Export | - | x | |
| Deploy | Call | - | x | |
| Deploy | Phone | x |
The permission grid appears only when Restrict permissions is switched on.
Copy the key into PopMCP
Click Copy in the dialog and paste the key_... value into PopMCP's API key field, then connect.
API Keys
Retell shows the full value only once.
Connect in PopMCP
Open your workspace, choose Retell AI in the marketplace, and fill in the connect dialog:
| Field | What to enter |
|---|---|
| API keysecret | Retell dashboard (dashboard.retellai.com) → Settings → API Keys → create/copy a key. Sent as the Authorization: Bearer header. Stored encrypted; used server-side only. The connection is locked to this key's Retell account.Encrypted with AES-256-GCM on save and never shown again. |
PopMCP verifies the credential against Retell AI immediately. On success the connection flips to Verified and its MCP tools are provisioned.
Verify it worked
PopMCP shows the Retell connector as Connected and names your workspace. Asking for recent calls or the list of agents returns real rows instead of an auth error.
Troubleshooting
401 Unauthorized on every call
Why: The key was mistyped, truncated on paste, or has since been deleted or rotated in the dashboard.
Fix: Open Settings > API Keys, delete the stale entry, click Add to mint a fresh key, and paste the whole key_ string with no surrounding spaces. The full value is shown only at creation, so a lost key has to be replaced rather than recovered.
Some tools work but calls or agent edits return 403
Why: The key was created with Restrict permissions on and the relevant permission left at No Access or Read.
Fix: Edit the key in Settings > API Keys. Raise Call to Edit for outbound calls and Agent to Edit for agent changes, or switch Restrict permissions off entirely.
PopMCP sees no agents even though the connection succeeded
Why: The key belongs to a different Retell workspace than the one holding your agents.
Fix: Switch workspaces with the top-left switcher, mint a key there, and reconnect.
Outbound calls are rejected with a concurrency error
Why: The workspace has hit its simultaneous-call quota, which defaults to 20 on Pay-As-You-Go.
Fix: Open Settings > Limits and click Adjust Concurrency on the Concurrent Calls Limit card, or enable concurrency burst, then retry.