`wrapMcpServerWithSentry` defaults `recordInputs` / `recordOutputs` to `true` (via `dataCollection.genAI`) |

[tiagovilasboas]

Static review of public source at commit b633c8153250. No traffic was sent to any Sentry environment.

MCP server instrumentation resolves capture flags like this:

packages/core/src/integrations/mcp-server/transport.ts:

function resolveMcpOptions(options: McpServerWrapperOptions): ResolvedMcpOptions {
  // ...
  const genAI = getClient()?.getDataCollectionOptions().genAI;
  return {
    recordInputs: options.recordInputs ?? genAI?.inputs ?? true,
    recordOutputs: options.recordOutputs ?? genAI?.outputs ?? true,
  };
}

dataCollection.genAI itself documents { inputs: true, outputs: true } as the default. So a bare Sentry.wrapMcpServerWithSentry(server) will put tool/prompt arguments and results on spans (tokens, file paths, user content, etc.) unless the operator remembers to pass { recordInputs: false, recordOutputs: false } or tighten dataCollection.genAI.

That is great for AI debugging; it is a surprising default for MCP servers that often proxy secrets and private data.

Suggested change:

• Default MCP wrapper capture to false / metadata-only unless recordInputs/recordOutputs or dataCollection.genAI is explicitly enabled; or
• Keep genAI defaults but make wrapMcpServerWithSentry() document and prefer explicit { recordInputs, recordOutputs } with a one-time startup log when both resolve to true.
• Mirror the scrubbing posture already used for network PII in piiFiltering.ts.

Severity: low–medium / privacy & data-minimization defense-in-depth (parallel to the Python SDK EventScrubber recursive default discussion). Not claiming a Sentry platform vulnerability. No proof-of-concept.

Happy to send a focused PR if useful.

[linear-code]

JS-3752

[Lms24]

Hi @tiagovilasboas, I need some clarifications on this issue:

• are you reporting a bug, or requesting that the default values of dataCollection get changed?
• dataCollection defaulting to true for recording inputs and outputs is expected behaviour, see docs

If your report is a bug, please provide a minimal reproduction, at least your SDK setup, used SDK and version. Also, please follow our bug template, because this issue looks completely AI-generated at the moment.

[tiagovilasboas]

Hi @Lms24 — thanks for the clarification ask.

This is not a bug report against current dataCollection behavior. I agree with the docs: when dataCollection is used, genAI recording inputs/outputs defaults to true unless you opt out (Data Collected — LLM Inputs And Responses).

What I meant to file is an enhancement / secure-by-default request scoped to MCP instrumentation, not “dataCollection is broken.”

Evidence still on current main in packages/core/src/integrations/mcp-server/transport.ts:

function resolveMcpOptions(options: McpServerWrapperOptions): ResolvedMcpOptions {
  if (options.recordInputs !== undefined && options.recordOutputs !== undefined) {
    return {
      recordInputs: options.recordInputs,
      recordOutputs: options.recordOutputs,
    };
  }

  const genAI = getClient()?.getDataCollectionOptions().genAI;

  return {
    recordInputs: options.recordInputs ?? genAI?.inputs ?? true,
    recordOutputs: options.recordOutputs ?? genAI?.outputs ?? true,
  };
}

Two points that matter for MCP specifically:

1. Even when the operator never sets dataCollection / genAI, the wrapper still falls through to ?? true, so a bare Sentry.wrapMcpServerWithSentry(server) records tool/prompt args and results.
2. MCP payloads often carry secrets and private user content (tokens, file paths, messages), which is a harsher default surface than typical LLM chat spans — easy to miss if you only read the genAI docs in an AI-integration context.

Concrete asks (any one is fine):

1. Safer MCP-wrapper defaults (recordInputs / recordOutputs false unless explicitly set), or
2. Keep the current resolution, but require/encourage explicit { recordInputs, recordOutputs } on the wrapper and/or a clear startup note when both resolve to true.

No crash / incorrect-span reproduction — the concern is default posture for MCP. Happy to reframe/relabel as enhancement, or open a focused docs/PR if you’d rather keep the current defaults.