Summary

• OpenAI-compatible providers (and proxies) reject MCP tool schemas where all parameters are optional, emitting a 500 error: "None is not of type 'array'" — the JSON Schema serializer outputs required: null instead of required: [] for such tools.
• Promotes one semantically appropriate parameter to required in each of the 4 affected tools so the schema always has a valid required array.
• Runtime behavior is fully preserved via fallback logic where needed.

Changes

• background_cancel: all (boolean) promoted to required; moved before taskId. Callers must now explicitly pass all=false when cancelling by ID. Updated BackgroundCancelArgs interface to match.
• session_list: limit promoted to required. Pass 0 to mean "no limit". Updated description and SessionListArgs interface to match.
• team_create: leadSessionId promoted to required and moved first. Pass "" to use the current session. Added empty-string fallback in execute: (leadSessionId && leadSessionId.length > 0 ? leadSessionId : undefined) ?? runtimeContext.sessionID.
• team_list: scope promoted to required. Callers must now pass "user", "project", or "all" explicitly. Removed ?? "all" fallback from execute since the value is always present.

Testing

Verified by running against an OpenAI-compatible proxy (new-api/gpt-5.5, github-copilot/gpt-5.2-codex) that previously rejected these tool schemas with the None is not of type 'array' error. All 4 tools now pass schema validation and execute correctly.

Summary by cubic

Fixes schema incompatibility with OpenAI strict function calling by ensuring tool arg schemas never have all-optional parameters. One parameter is now required in background_cancel, session_list, team_create, and team_list, while preserving runtime behavior via fallbacks.

• Migration
  • background_cancel: all is required. Set true to cancel all tasks; set false and provide taskId to cancel one.
  • session_list: limit is required. Use 0 for no limit.
  • team_create: leadSessionId is required. Pass "" to use the current session.
  • team_list: scope is required. Pass user, project, or all.

^{Written for commit 40cb283. Summary will update on new commits. Review in cubic}