Empty MCP dispatch registry vs advertised traycer_* tool surface — agents report false capability loss and misroute spend

[kyledempster7]

devin CLI 3000.6.14, macOS arm64, gui/devin swe-2-max, Traycer host 1.3.1 — 2026-09-13 ~08:25 UTC.

Agent-side harm from session-injected MCP servers that never reach the dispatch registry (companion to traycerai/traycer#873, #1858, #1877).

Sequence observed this session:

1. Resumed session's system prompt still advertised traycer_a2a/traycer-browser under "Available MCP Servers" and instructed the agent to use traycer_send_message, traycer_get_self, traycer_agent_selection_guide.
2. mcp_list_servers returned {"servers":[]}; mcp_list_tools("traycer_a2a") → "not found in configuration".
3. The agent reported "I cannot create persistent named agents" to the user — a false capability report. The traycer CLI fallback was functional the whole time, but the prompt-vs-registry mismatch is invisible until the agent burns turns discovering it.
4. When pushed, the agent used traycer agent create — which is billable on creation — duplicating two seats the user had already provisioned. Root cause of the overspend was the agent reasoning from a tool surface that didn't exist.

Asks for devin-cli:

• If injected servers fail to register in the dispatch registry, do not render their tool names/instructions into the prompt — the two must never disagree.
• mcp_list_servers should return CLI-backed servers or a warning when the registry is empty but servers were injected.
• Repro path: resume/compact a session that had traycer_a2a injected; observe prompt still advertises it while the registry is empty.