{"record":{"id":"797532f781a4ca47","repo":"vercel/ai","slug":"the-acp-agent-does-not-advertise-support-for-val","errorCode":null,"errorMessage":"The ACP agent does not advertise support for ${value.type.toUpperCase()} MCP servers.","messagePattern":"The ACP agent does not advertise support for (.+?) MCP servers\\.","errorType":"exception","errorClass":"HarnessBridgeCapabilityUnsupportedError","httpStatus":null,"severity":"error","filePath":"packages/harness-acp/src/v1/bridge/index.ts","lineNumber":656,"sourceCode":"  return Object.entries(mcpServers).map(([name, value]) => {\n    if (!isRecord(value)) {\n      throw new Error(\n        `ACP MCP server ${JSON.stringify(name)} must be configured with an object value.`,\n      );\n    }\n    if (value.type === 'acp') {\n      throw new HarnessBridgeCapabilityUnsupportedError({\n        harnessId: bridgeType,\n        message:\n          'ACP-transport MCP servers require client-side mcp/connect handling, which this harness does not provide.',\n      });\n    }\n    const mcpCapabilities = initialization.agentCapabilities?.mcpCapabilities;\n    if (\n      (value.type === 'http' && mcpCapabilities?.http !== true) ||\n      (value.type === 'sse' && mcpCapabilities?.sse !== true)\n    ) {\n      throw new HarnessBridgeCapabilityUnsupportedError({\n        harnessId: bridgeType,\n        message: `The ACP agent does not advertise support for ${value.type.toUpperCase()} MCP servers.`,\n      });\n    }\n    return { ...value, name } as acp.McpServer;\n  });\n}\n\nfunction unknownUsage() {\n  return {\n    inputTokens: {\n      total: undefined,\n      noCache: undefined,\n      cacheRead: undefined,\n      cacheWrite: undefined,\n    },\n    outputTokens: {\n      total: undefined,","sourceCodeStart":638,"sourceCodeEnd":674,"githubUrl":"https://github.com/vercel/ai/blob/69428b1f8b037e4d118fb4853428d5c4e620493c/packages/harness-acp/src/v1/bridge/index.ts#L638-L674","documentation":"Error \"The ACP agent does not advertise support for ${value.type.toUpperCase()} MCP servers.\" thrown in vercel/ai.","triggerScenarios":"Thrown at packages/harness-acp/src/v1/bridge/index.ts:656 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":[],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"69428b1f8b037e4d118fb4853428d5c4e620493c","analyzedAt":"2026-08-30T12:32:21.016Z","schemaVersion":2},"datasetVersion":"2026-08-30T13:17:10.514Z"}