{"record":{"id":"16d2238b1eb8d1a2","repo":"openai/codex","slug":"events-list-returned-an-unexpected-mcp-result","errorCode":null,"errorMessage":"events/list returned an unexpected MCP result","messagePattern":"events/list returned an unexpected MCP result","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"codex-rs/codex-mcp/src/resource_client.rs","lineNumber":247,"sourceCode":"        Ok(McpResourceReadResult { contents })\n    }\n\n    /// Lists the events advertised by the hosted Plugin Runtime.\n    pub async fn list_events(&self) -> Result<McpEventCatalogSnapshot> {\n        let (connections, _) = self\n            .runtime\n            .latest_connections_for_event_server(CODEX_APPS_MCP_SERVER_NAME)?;\n        let cache_key = McpResourceClientCacheKey(Arc::downgrade(&connections));\n        let (managed, request_timeout) = connections\n            .client_by_name(CODEX_APPS_MCP_SERVER_NAME)\n            .await?;\n        let result = managed\n            .client\n            .send_custom_request_with_timeout(\"events/list\", /*params*/ None, request_timeout)\n            .await\n            .context(\"events/list failed for hosted Plugin Runtime\")?;\n        let ServerResult::CustomResult(result) = result else {\n            return Err(anyhow!(\"events/list returned an unexpected MCP result\"));\n        };\n        let result = result\n            .result_as::<McpEventListResult>()\n            .context(\"events/list returned invalid event definitions\")?;\n\n        Ok(McpEventCatalogSnapshot {\n            cache_key,\n            events: result.events,\n        })\n    }\n\n    /// Opens an MCP event subscription with the supplied event arguments.\n    pub async fn open_event_stream(\n        &self,\n        event_name: &str,\n        arguments: &Value,\n        request_meta: Option<&Map<String, Value>>,\n    ) -> Result<McpEventStream> {","sourceCodeStart":229,"sourceCodeEnd":265,"githubUrl":"https://github.com/openai/codex/blob/339751715c64496cb86246bfb3935f40e309dd3d/codex-rs/codex-mcp/src/resource_client.rs#L229-L265","documentation":"Error \"events/list returned an unexpected MCP result\" thrown in openai/codex.","triggerScenarios":"Thrown at codex-rs/codex-mcp/src/resource_client.rs:247 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Fix the MCP server to return a spec-conformant result for events/list."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"339751715c64496cb86246bfb3935f40e309dd3d","analyzedAt":"2026-08-25T05:35:09.876Z","schemaVersion":2},"datasetVersion":"2026-08-25T06:17:31.827Z"}