OAuth login still waiting for callback — diagnosis

Agent diagnostic brief

Exact symptom

MCP server needs authentication

Where it has been observed

remote HTTP MCP
plugin/runtime challenge on macOS

Likely distinct causes

The host did not initiate its OAuth flow from the presented state.
A late 401 challenge did not transition the plugin server to an authenticatable UI state.

How to distinguish them

Observe browser launch, client event log, and network activity while activating authentication.
If there is zero request activity, stop: protected-resource metadata, callback, token, and scope stages have not executed.
Distinguish an initial connect action from a late/runtime 401 challenge in a plugin-provided server.
The login process completes and a subsequent independent configuration/status readback reports authenticated OAuth state.

Current approaches

Verify that the MCP host actually initiated OAuth (solution-auth-flow-not-initiated, revision 1).

Known obsolete approaches

Do not apply historical protocol or client workarounds without checking the current version boundary.
Do not disable authentication, issuer/audience checks, schema validation, sandboxing, or enterprise policy merely to suppress the symptom.

Versions and freshness

Two Cursor forum reports in 2026 cover initial and late/runtime challenge paths; product UI is volatile.
Editorial and primary-source review date: 2026-09-10.
Observed 2026-07-29; current local Codex CLI help rechecked 2026-09-11
Historical evidence reviewed 2026-09-11.

What remains unknown

Not established: OAuth metadata is malformed.
Not established: The session is expired.
Not established: The callback URL is wrong.
Current behavior outside the reviewed clients, versions, and environments remains unknown.
Independent reproduction by another operator remains unestablished.

Deeper evidence

Problem

MCP server needs authentication but the host never starts OAuth

Observed symptom

The UI says authentication is needed, but clicking connect/authenticate opens no browser and emits no metadata or authorization request.
Observed in 2 reviewed public artifacts; this is not a claim that only that many reports exist.
The appearance of an authorization URL could be mistaken for completed MCP authentication even though the local callback and CLI command had not finished.

Operator goal

initiate OAuth using HTTP OAuth.

Current understanding

No network request means discovery/token hypotheses have not yet been exercised.
The host did not initiate its OAuth flow from the presented state.
A late 401 challenge did not transition the plugin server to an authenticatable UI state.
A Grade A same-operator execution observed: Interactive login exited successfully and a separate status readback reported the configured MCP server enabled with OAuth.

Known limitations

Applies only to Cursor and the stated version/environment boundary until current behavior is rechecked.
A source-reported workaround is evidence from that report, not a Knowledge for Agents execution or universal Outcome.

Known negative results

Cursor remote MCP connect action sends no OAuth request: Known UI-flow report; no universal fixed version established.
Cursor runtime OAuth challenge never exposes Authenticate: Vendor response said the endpoint/challenge was recognized and issue tracked.
No external report was promoted to an actual platform Attempt or Outcome.

Primary and recurrence sources

OpenAI Codex CLI reference
Primary · Primary documentation · Date not supplied · Reviewed 2026-09-11 · Rights: allowed_to_summarize
Current primary material reviewed for Historical Corpus 1: OpenAI Codex CLI reference.
Cursor MCP documentation
Primary · Official product documentation · Date not supplied · Reviewed 2026-09-10 · Rights: allowed_to_summarize
Current stdio executable requirements, transport types, tool exposure, OAuth support, and enterprise policy boundaries.
MCP 2026-07-28 Authorization
Primary · Official specification · Date not supplied · Reviewed 2026-09-10 · Rights: allowed_to_summarize
Current HTTP authorization requirements, protected-resource metadata, authorization-server discovery, resource binding, token handling, and step-up scope behavior.
MCP authorization specification
Primary · Primary specification · Date not supplied · Reviewed 2026-09-11 · Rights: allowed_to_summarize
Current primary material reviewed for Historical Corpus 1: MCP authorization specification.
Cursor remote MCP connect action sends no OAuth request
Recurrence · Vendor forum report · 2026-02-06 · Reviewed 2026-09-10 · Rights: link_only
Zero network activity is a discriminator: discovery cannot be the failing step if the flow never starts.
Cursor runtime OAuth challenge never exposes Authenticate
Recurrence · Vendor forum report · 2026-08-31 · Reviewed 2026-09-10 · Rights: link_only
A host can fail to transition to needs-auth even when the server challenge is present.

Rights and provenance

Origin

Based on a real operator execution; identifying project details removed.

Rights

State: allowed_to_summarize
Review basis: Owner-authorized factual synthesis of the operator's own execution, independently written from reviewed current primary sources; no transcript expression is published.

Editorial review date

2026-09-11

Known approaches

solution · Revision 2

Verify that the MCP host actually initiated OAuth

Production corpus importer · 2026-09-11T00:10:00.000Z
Operator Knowledge for Agents editorial · Historical operator record · Digital source: trainedAlgorithmicMedia · Rights: owned

## Candidate action - Verify that the MCP host actually initiated OAuth. Start by capturing the first failed stage in the exact client process and version. Apply only the first evidence-backed correction below, then repeat the same observation from process start through the next protocol boundary. This is a candidate diagnostic procedure, not a claim that the external reports establish a universal fix. ## Applicability - Use when the observed symptom and operation match MCP server needs authentication. - Observed product scope: Cursor. - No network request means discovery/token hypotheses have not yet been exercised. - Historical execution boundary: Codex CLI and remote MCP; interactive OAuth login. ## Procedure - Observe browser launch, client event log, and network activity while activating authentication. - If there is zero request activity, stop: protected-resource metadata, callback, token, and scope stages have not executed. - Distinguish an initial connect action from a late/runtime 401 challenge in a plugin-provided server. - Use the host's documented authentication action or current release path for the specific initial/late challenge state. - Where the host presents a safe authorization URL, open it through the documented flow rather than constructing one manually. - Escalate with a minimal UI/network trace if the host never transitions to OAuth; do not edit server metadata without evidence. - Run the current host's documented MCP login action, complete the browser callback, wait for successful command exit, then recheck the server's authentication state. Verify: The login command completed successfully and the configuration readback showed the server enabled with OAuth. ## Limitations - The procedure does not establish behavior for unreviewed client versions, operating systems, proxies, or authorization providers. - A successful retry proves only that invocation; preserve logs and the changed variable before attributing cause. ## Obsolete approaches - Do not copy a historical workaround across protocol eras or client products without revalidating applicability. - Do not bypass security controls, put secrets in URLs/logs, or make unmanaged cache edits as a default recovery step. ## Negative results - Cursor remote MCP connect action sends no OAuth request: Known UI-flow report; no universal fixed version established. - Cursor runtime OAuth challenge never exposes Authenticate: Vendor response said the endpoint/challenge was recognized and issue tracked. - No external report was promoted to an actual platform Attempt or Outcome. ## Evidence boundary - Grounded in primary sources src-cursor-mcp-current, src-mcp-auth-20260728 and recurrence artifacts src-auth-cursor-init-150962, src-auth-cursor-late-170058. - External success claims remain external source evidence. Only manifest execution records count as Knowledge for Agents Attempts or Outcomes. - A Grade A same-operator execution on 2026-07-29 observed: Interactive login exited successfully and a separate status readback reported the configured MCP server enabled with OAuth. - This is not an independent reproduction. ## What remains unknown - Not established: OAuth metadata is malformed. - Not established: The session is expired. - Not established: The callback URL is wrong. - Current behavior outside the reviewed clients, versions, and environments remains unknown. - Independent reproduction by another operator remains unestablished.

Applicability

State

partial

Text

Applies only when the first failed stage matches this record in Cursor.

Facts

Component: host authentication-state transition
Operation: initiate OAuth
Protocol: HTTP OAuth

Provenance disclosure

Based on a real operator execution; identifying project details removed.

Historical date

2026-07-29

Verification grade

Operator relationship

same_operator

Independent reproduction

false

Pack

Candidate action: Verify that the MCP host actually initiated OAuth. Start by capturing the first failed stage in the exact client process and version. Apply only the first evidence-backed correction below, then repeat the same observation from process start through the next protocol boundary. This is a candidate diagnostic procedure, not a claim that the external reports establish a universal fix.
Applicability: Use when the observed symptom and operation match MCP server needs authentication.
Observed product scope: Cursor.
No network request means discovery/token hypotheses have not yet been exercised.
Historical execution boundary: Codex CLI and remote MCP; interactive OAuth login.
Steps: Observe browser launch, client event log, and network activity while activating authentication.
If there is zero request activity, stop: protected-resource metadata, callback, token, and scope stages have not executed.
Distinguish an initial connect action from a late/runtime 401 challenge in a plugin-provided server.
Use the host's documented authentication action or current release path for the specific initial/late challenge state.
Where the host presents a safe authorization URL, open it through the documented flow rather than constructing one manually.
Escalate with a minimal UI/network trace if the host never transitions to OAuth; do not edit server metadata without evidence.
Run the current host's documented MCP login action, complete the browser callback, wait for successful command exit, then recheck the server's authentication state. Verify: The login command completed successfully and the configuration readback showed the server enabled with OAuth.
Limitations: The procedure does not establish behavior for unreviewed client versions, operating systems, proxies, or authorization providers.
A successful retry proves only that invocation; preserve logs and the changed variable before attributing cause.
Obsolete approaches: Do not copy a historical workaround across protocol eras or client products without revalidating applicability.
Do not bypass security controls, put secrets in URLs/logs, or make unmanaged cache edits as a default recovery step.
Negative results: Cursor remote MCP connect action sends no OAuth request: Known UI-flow report; no universal fixed version established.
Cursor runtime OAuth challenge never exposes Authenticate: Vendor response said the endpoint/challenge was recognized and issue tracked.
No external report was promoted to an actual platform Attempt or Outcome.
Evidence boundary: Grounded in primary sources src-cursor-mcp-current, src-mcp-auth-20260728 and recurrence artifacts src-auth-cursor-init-150962, src-auth-cursor-late-170058.
External success claims remain external source evidence. Only manifest execution records count as Knowledge for Agents Attempts or Outcomes.
A Grade A same-operator execution on 2026-07-29 observed: Interactive login exited successfully and a separate status readback reported the configured MCP server enabled with OAuth.
This is not an independent reproduction.
What remains unknown: Not established: OAuth metadata is malformed.
Not established: The session is expired.
Not established: The callback URL is wrong.
Current behavior outside the reviewed clients, versions, and environments remains unknown.
Independent reproduction by another operator remains unestablished.

Rights

State: allowed_to_summarize
Review basis: Original diagnostic procedure synthesized from owner-authorized execution facts and linked current primary sources; no private source code, logs, or transcript expression is published.

Source ids

src-cursor-mcp-current
src-mcp-auth-20260728
src-auth-cursor-init-150962
src-auth-cursor-late-170058
src-codex-cli-reference-current
src-mcp-authorization-20251125