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plat 087
| Coordination | Value |
|---|---|
| Assigned agent | unassigned |
| Ticket state | open |
| Last synchronized | 2026-08-11 |
- Priority: P1
- Owner: child-session tool registration / agent-spec materialization
-
Source workflow: Instagram, scheduled run
schedule-manual--bae435e5_1786432476119732000 - Related: PLAT-003 (managed DB capability) and PLAT-053 (background workshop tool inheritance). Those fixes cover narrower session families; this is a normal message-sequence child session.
Instagram's route-build-video and route-generate-illustrations child
sessions were given a prompt that listed workspace_advanced,
workspace_browser, and workflow_db with their tool rosters. The exact same
sessions then failed calls with:
tools_unavailable: server_unavailable=[workspace_advanced workspace_browser]
... configured for this agent but currently have zero registered tools
The missing tools were not guesses: generate_music, read_image, and the
DB route were listed in the child prompt. workflow_db had a narrow HTTP
workaround, but binary tools did not, so the orchestration had to replace the
music-generation action itself. This happened twice in the same producing run
and the concern has seen_count=2 in
Workflow/instagram/db/db.sqlite (61347449b57c07bd).
One part of child-session creation builds the prompt/tool index; another part registers the real MCP tools. They can disagree. The agent is told a tool is available, follows the supplied name, and then receives a server-outage error because the advertised server was created with zero callable tools.
- Agents waste turns retrying names that were already correct.
- Capabilities that have no shell/HTTP fallback (for example image/audio operations) cannot be performed at all.
- The prompt misleads both the agent and the operator: it looks like an agent mistake, but the platform created an impossible contract.
Use one canonical child AgentSpec to derive both:
- the tool index shown to the child, and
- the actual MCP/custom-tool registrations for that child session.
Before the agent starts, validate advertised tools ⊆ registered tools and
either register the missing capability or remove it from the prompt. A server
with zero tools must be treated as unavailable at construction time, not after
the model has spent a turn trying it.
- A message-sequence child that advertises
generate_music,read_image, or a managed DB tool can invoke it in the same session. - If a configured provider cannot start, its tools are omitted from the prompt and a deterministic startup diagnostic names the unavailable provider.
- Cover normal message-sequence children separately from PLAT-003's workflow DB execution steps and PLAT-053's workshop background children.
Auto-synced from docs/ on main. Edit there, not here.