René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Clarify debug_attach_sim argument combinations for PID attach","articleBody":"## Summary\n\nWhen using the `debug_attach_sim` MCP tool from Claude Code, the tool schema made it look like `bundleId`, `pid`, and `waitFor` could be supplied together. In practice, those fields are mutually constrained, and invalid combinations fail only after the tool call is made.\n\n## What happened\n\nI was debugging a live iOS Simulator app and wanted to attach LLDB to an already-running process while preserving simulator/app state.\n\nThe schema exposed these fields:\n\n- `bundleId: string`\n- `pid: integer`\n- `waitFor: boolean`\n- `continueOnAttach: boolean`\n- `makeCurrent: boolean`\n\nBecause `bundleId` and `pid` both appeared required/available, I initially supplied both. That failed. I then tried PID attach with `waitFor: true`, which also failed with an invalid option combination. The working form was effectively PID-only attach with an empty bundle id and no wait:\n\n```json\n{\n  \"bundleId\": \"\",\n  \"pid\": 12345,\n  \"waitFor\": false,\n  \"continueOnAttach\": true,\n  \"makeCurrent\": true\n}\n```\n\n## Why this is confusing\n\nFor an MCP client/agent, the schema communicates what fields are required and valid. If a field appears required even though it is only required for one mode, the agent tends to provide it. That can push the model into invalid combinations such as:\n\n- `bundleId` + `pid`\n- `pid` + `waitFor: true`\n\nThe correct usage is discoverable only by failing calls, which is especially painful during debugging because failed attach attempts interrupt the LLDB workflow.\n\n## Suggested improvements\n\nCould the `debug_attach_sim` schema and/or tool error messages make the attach modes explicit?\n\nFor example:\n\n1. Model the inputs as one of two attach modes:\n   - attach by bundle id: `bundleId` required, `pid` omitted, `waitFor` allowed\n   - attach by PID: `pid` required, `bundleId` omitted, `waitFor` false/omitted\n2. Make `bundleId` optional when `pid` is provided, rather than requiring callers to pass `\"\"`.\n3. Return an error message that says exactly which combinations are valid, e.g.:\n   - `Provide either bundleId or pid, not both.`\n   - `waitFor is only valid when attaching by bundleId.`\n4. Add a short example for attaching to an already-running simulator app by PID.\n\n## Environment/context\n\n- Tool: XcodeBuildMCP via Claude Code MCP tools\n- Workflow: simulator debugging / LLDB attach\n- Goal: attach to an existing running app process without rebooting, reinstalling, or losing app state\n\nThanks for maintaining this tool. Once attached, `debug_lldb_command` worked well for raw LLDB commands like `process status`, `bt`, `frame variable`, and `po`.","author":{"url":"https://github.com/dpearson2699","@type":"Person","name":"dpearson2699"},"datePublished":"2026-05-13T17:37:58.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/417/XcodeBuildMCP/issues/417"}