feat(mcp): add named tools for the OpenAI plugin

[waleedlatif1]

Summary

• Add a public plugin MCP profile that advertises eleven individually named workspace, workflow, run, and table tools with contract-derived input schemas and explicit safety annotations.
• Keep dispatch through existing authorized v2 operations, require an exact OAuth resource audience, and serve the public ownership challenge for directory verification.

Type of Change

• New feature

Testing

• Regression cases for public tool discovery, hidden executor rejection, write-scope challenges, host routing, and OAuth resource binding; verified failures before implementation.
• Full repository lint, type-check, all 58 audits, docs-manifest check, block-registry check, and actionlint passed.
• Script suite passed (386 tests) with one worker and a 30-second timeout. The default run timed out in unrelated release-script tests under host load.
• All 20 workspace test tasks passed, including 36,756 app tests, with two workers and a 30-second default timeout.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

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1 Skipped Deployment

Project	Deployment	Actions	Updated
docs	Skipped		Oct 9, 2026 12:40am UTC

[cubic-dev-ai]

2 issues found across 14 files

Confidence score: 3/5

• A root-path SIM_MCP_URL makes the OpenAI endpoint and protected-resource metadata return 404 in host-routing.ts. Normalize the root pathname before building those routes.
• The instructions in openai.ts can make manual draft runs fail because the tool rejects streaming. Keep manual runs synchronous and reserve async execution for run-ID polling.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="apps/sim/lib/api/mcp/host-routing.ts">

<violation number="1" location="apps/sim/lib/api/mcp/host-routing.ts:50">
P2: A root-path `SIM_MCP_URL` makes the OpenAI endpoint and its protected-resource metadata return 404: `mcp.pathname` is `/`, so these checks expect `//openai` rather than `/openai`. Normalize the root pathname before appending `/openai` in both checks.</violation>
</file>

<file name="apps/sim/lib/api/mcp/openai.ts">

<violation number="1" location="apps/sim/lib/api/mcp/openai.ts:70">
P2: This instruction makes manual draft runs fail: the contract permits them only synchronously or streamed, and this MCP tool rejects streaming. Direct manual runs synchronously; reserve async execution and run-ID polling for deployed runs.</violation>
</file>

_{Turn on auto-fix | Re-trigger cubic}

[cubic-dev-ai]

P2: A root-path SIM_MCP_URL makes the OpenAI endpoint and its protected-resource metadata return 404: mcp.pathname is /, so these checks expect //openai rather than /openai. Normalize the root pathname before appending /openai in both checks.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. At apps/sim/lib/api/mcp/host-routing.ts, line 50:

<comment>A root-path `SIM_MCP_URL` makes the OpenAI endpoint and its protected-resource metadata return 404: `mcp.pathname` is `/`, so these checks expect `//openai` rather than `/openai`. Normalize the root pathname before appending `/openai` in both checks.</comment>

<file context>
@@ -37,15 +37,25 @@ export function resolveSimMcpHostPath(
   }
   if (pathname === mcp.pathname) return SIM_MCP_ROUTE_PATH
   if (pathname === `${PROTECTED_RESOURCE_METADATA}${mcp.pathname}`) return internalMetadataPath
+  if (pathname === `${mcp.pathname}/openai`) return openAiPath
+  if (pathname === `${PROTECTED_RESOURCE_METADATA}${mcp.pathname}/openai`) {
+    return openAiMetadataPath
</file context>

[cubic-dev-ai]

P2: This instruction makes manual draft runs fail: the contract permits them only synchronously or streamed, and this MCP tool rejects streaming. Direct manual runs synchronously; reserve async execution and run-ID polling for deployed runs.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. When an issue isn't valid or won't be fixed in this PR, reply in its thread with the reason and then resolve the thread. At apps/sim/lib/api/mcp/openai.ts, line 70:

<comment>This instruction makes manual draft runs fail: the contract permits them only synchronously or streamed, and this MCP tool rejects streaming. Direct manual runs synchronously; reserve async execution and run-ID polling for deployed runs.</comment>

<file context>
@@ -0,0 +1,187 @@
+    operation: 'executeWorkflow',
+    title: 'Run workflow',
+    description:
+      'Run the Sim workflow the user selected with the supplied input. Its configured steps can change or delete data, send messages, contact external services, and consume usage. Inspect the workflow and obtain authorization for those effects before running. Streaming is unsupported; use async execution and read the returned run ID to check completion. Never automatically start another run after an uncertain result.',
+    readOnly: false,
+    destructive: true,
</file context>

[greptile-apps]

Confidence Score: 4/5

[High impact] Adds a new public MCP endpoint for OpenAI plugin integration.

Fix root-host routing before merging so supported self-hosted configurations can connect the plugin.

Findings

1.  Plugin fails on root hosts ▶

Summary

Adds an OpenAI MCP profile with eleven named tools backed by existing v2 operations.

• Publishes contract-derived inputs, safety hints, and profile-specific OAuth metadata.
• Keeps exact OAuth audience checks and rejects hidden executors.
• Adds a public ownership challenge and dedicated-host routing.
• Root-host MCP configurations need a routing fix before merging.

Diagram

%%{init: {'theme': 'neutral'}}%%
flowchart LR
  Client[OpenAI client] --> Host[Plugin URL]
  Host --> Route["/api/mcp/openai"]
  Route --> Auth[Check credential and resource]
  Auth --> Scope[Check operation scope]
  Scope --> Tools[Resolve named tool]
  Tools --> Dispatch[Forward original credential]
  Dispatch --> V2[Existing authorized v2 route]
  V2 --> Result[Bounded JSON tool result]
  Result --> Client

Loading

_{Reviews (1) · Last reviewed commit: "feat(mcp): add named tools for the OpenA..." · Reviewed by Greptile}

[greptile-apps]

Plugin fails on root hosts

With SIM_MCP_URL=https://mcp.example, getSimMcpUrl('openai') advertises /openai, but these checks expect //openai because mcp.pathname is /. The advertised endpoint and its OAuth metadata therefore return 404 on the dedicated host.

Build both checks from new URL(getSimMcpUrl('openai')).pathname so root-host configurations work too.

Knowledge Base Used: MCP server and tool access