feat(agent-as-tool): configure sub-agents as callable tools by unrealandychan · Pull Request #197 · BerriAI/litellm-agent-platform

unrealandychan · 2026-05-19T04:39:35Z

Closes #193.

Closes BerriAI#193. Schema: - prisma/schema.prisma: add `agent_tools` JSON field to Agent - prisma/migrations/0006_agent_tools: ALTER TABLE migration Types / Validation: - src/server/types.ts: AgentToolSpec interface + AgentToolSpecSchema zod schema; agent_tools field on CreateAgentBody, UpdateAgentBody, Agent interface; toApiAgent() maps the new field - src/server/auth/agent-token.ts: extend AgentScope to include 'tool' API: - PATCH /agents/:id — now accepts agent_tools (UpdateAgentBody) - GET /agents/:id/tools — list sub-agent tools - PUT /agents/:id/tools — replace tools list (validates ref'd agents exist, guards against self-reference) - POST /agents/:id/tools/invoke — invoke a sub-agent synchronously; cold-starts a Session, sends the input, returns the response text. Auth: per-agent token (scope=tool) or master key. Guard: sub_agent_id must be in the caller's agent_tools list. Runtime injection: - src/server/k8s.ts: inject AGENT_TOOLS_JSON into every sandbox pod so harnesses can register sub-agents as first-class tools UI: - src/components/agent-as-tool-picker.tsx: new component — add/remove/edit sub-agent tools with an agent selector, tool name input, and description textarea. Validates alphanumeric tool names, caps at 10 entries. - src/lib/api.ts: add agent_tools to AgentRow + UpdateAgentRequest - src/app/agents/[id]/page.tsx: wire AgentAsToolPicker into agent settings with optimistic updates

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Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds “sub-agent tools” so an orchestrator agent can delegate work to configured sub-agents via a persisted agent_tools list, exposed in the UI/API, and injected into the harness as AGENT_TOOLS_JSON.

Changes:

Add agent_tools to agent create/update schemas, API responses, and Kubernetes container env (AGENT_TOOLS_JSON).
Persist agent_tools in Prisma (schema + migration) and add managed API routes to set/list tools and invoke a sub-agent.
Add UI picker to configure sub-agent tools on the agent detail page.

Reviewed changes

Copilot reviewed 12 out of 13 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/server/types.ts	Adds `AgentToolSpec`, validation, request/response wiring, and `toApiAgent` mapping for `agent_tools`.
src/server/k8s.ts	Injects `AGENT_TOOLS_JSON` into sandbox container environment.
src/server/auth/agent-token.ts	Extends agent token scope to include `"tool"`.
src/lib/api.ts	Extends client-side types to include `agent_tools` in agent row/update request.
src/components/agent-as-tool-picker.tsx	New UI component to pick/configure sub-agent tools.
src/app/api/v1/managed_agents/agents/[agent_id]/tools/route.ts	New API route to list/replace an agent’s `agent_tools`.
src/app/api/v1/managed_agents/agents/[agent_id]/tools/invoke/route.ts	New API route to invoke a sub-agent as a tool with token scope `"tool"`.
src/app/api/v1/managed_agents/agents/[agent_id]/route.ts	Allows PATCHing `agent_tools` through the existing agent update route.
src/app/agents/[id]/page.tsx	Adds the picker UI and saves `agent_tools` via `updateAgent`.
prisma/schema.prisma	Adds `agent_tools` JSON column to `Agent`.
prisma/migrations/0006_agent_tools/migration.sql	Migration adding `agent_tools` JSONB column with default `[]`.
package.json	Bumps TypeScript version.

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+  }
+
+  const available = agents.filter(
+    (a) => !value.some((t, _idx) => t.agent_id === a.agent_id) || true,


+                <AgentAsToolPicker
+                  self_agent_id={agent.id}
+                  value={agent.agent_tools ?? []}
+                  disabled={agentToolsSaving}
+                  onChange={(tools) => {
+                    // Optimistic update
+                    setAgent({ ...agent, agent_tools: tools });
+                    void handleAgentToolsSave(tools);
+                  }}
+                />


+ * /api/v1/managed_agents/agents/{agent_id}/tools
+ *
+ * GET  — list sub-agent tools configured on this agent.
+ * POST — replace the agent's sub-agent tools list (idempotent upsert).


+const AgentToolSpecSchema = z.object({
+  agent_id: z.string().uuid(),
+  name: z
+    .string()
+    .min(1)
+    .max(64)
+    .regex(/^[a-zA-Z0-9_-]+$/, "name must be alphanumeric + underscores/hyphens"),
+  description: z.string().min(1).max(256),
+});


+const TIMEOUT_MS =
+  parseInt(process.env.AGENT_TOOL_INVOKE_TIMEOUT_MS ?? "120000", 10);


+import { harnessCreateSession, harnessSendMessage } from "@/server/harness";
+import { httpError, type AgentRow } from "@/server/types";
+import { wrap } from "@/server/route-helpers";
+import { env } from "@/server/env";


+    agent_tools: Array.isArray((row as Record<string, unknown>).agent_tools)
+      ? ((row as Record<string, unknown>).agent_tools as AgentToolSpec[])
+      : [],


greptile-apps · 2026-05-19T04:44:12Z

Greptile Summary

This PR introduces the "agent-as-tool" feature: a new database column (agent_tools JSONB), a UI picker for wiring sub-agents as callable tools, GET/PUT endpoints to manage the list, and a synchronous /tools/invoke endpoint that cold-starts a sub-agent pod and returns its response. Several correctness issues remain open from earlier review rounds and a new eager-save bug has been introduced in the picker.

Schema + migration: The agent_tools JSONB column is added cleanly with a safe IF NOT EXISTS guard and matching Prisma schema.
Invoke endpoint: Correctly guards callers by checking agent_tools membership, but each wait phase is given the full timeout independently (up to 2x the stated limit), and the sub-agent container is never explicitly stopped after a successful call.
Picker UI: addEntry() immediately fires onChange with a blank entry; the parent saves on every onChange, so every "Add sub-agent tool" click sends a request the server rejects with a 400 error.

Confidence Score: 3/5

Not safe to merge: the agent-as-tool flow is non-functional end-to-end and the picker UI errors on every Add click.

Three independent paths through the new feature each have a present defect: pods are minted tokens with only the memory scope so the invoke endpoint rejects every harness-initiated call with 401; the picker addEntry fires a save with blank fields the server rejects on every click; and the PATCH route bypasses the existence and self-reference checks enforced by the dedicated PUT /tools route.

src/server/k8s.ts (agentScopes must include tool), src/components/agent-as-tool-picker.tsx (addEntry fires saves with invalid data), src/app/api/v1/managed_agents/agents/[agent_id]/route.ts (PATCH missing validation), src/app/api/v1/managed_agents/agents/[agent_id]/tools/invoke/route.ts (double timeout, no stopTask on success)

Important Files Changed

Filename	Overview
src/app/api/v1/managed_agents/agents/[agent_id]/tools/invoke/route.ts	New invoke endpoint; contains the double-timeout bug and does not call stopTask after a successful run.
src/components/agent-as-tool-picker.tsx	Fires onChange with blank entries immediately on Add click, causing guaranteed 400 errors from the server on every interaction.
src/server/k8s.ts	Adds AGENT_TOOLS_JSON injection but agentScopes stays hardcoded to ["memory"] — pods cannot authenticate to the invoke endpoint.
src/app/agents/[id]/page.tsx	Wires AgentAsToolPicker with fire-and-forget save; correct pattern but amplifies the picker's premature-save bug.
src/app/api/v1/managed_agents/agents/[agent_id]/tools/route.ts	GET/PUT endpoints correct; AgentToolSpecSchema duplicated from types.ts.
src/app/api/v1/managed_agents/agents/[agent_id]/route.ts	PATCH handler missing existence and self-reference validation that PUT /tools enforces.
src/server/types.ts	Adds AgentToolSpec and AgentToolSpecSchema; schema duplicated in tools/route.ts.
src/server/auth/agent-token.ts	Adds "tool" to AgentScope union type; straightforward change.
prisma/migrations/0006_agent_tools/migration.sql	Correct migration with IF NOT EXISTS guard and purpose comment.
prisma/schema.prisma	Adds agent_tools Json field matching the migration.

_{Reviews (2): Last reviewed commit: "Update src/components/agent-as-tool-pick..." | Re-trigger Greptile}

greptile-apps · 2026-05-19T04:44:22Z

+  if (body.agent_tools !== undefined) {
+    data.agent_tools = body.agent_tools as unknown as Prisma.InputJsonValue;
+  }


PATCH route skips validation that the PUT /tools route enforces

The PUT /tools endpoint validates (a) each referenced agent_id exists in the database and (b) the agent cannot reference itself. Neither check is present here. Since the UI's handleAgentToolsSave calls updateAgent which hits this PATCH route, a user can persist a self-referential loop (agent A lists itself as a tool) or store non-existent agent_id references — both cases the invoke endpoint will mis-handle at runtime.

greptile-apps · 2026-05-19T04:44:23Z

+    sandboxUrl = await waitRunningGetUrl(task_arn, subAgent as AgentRow, TIMEOUT_MS);
+
+    await prisma.session.update({
+      where: { session_id },
+      data: { sandbox_url: sandboxUrl, phase: "waiting_http" },
+    });
+
+    await waitHttpReady(sandboxUrl, TIMEOUT_MS);


Each wait phase consumes its own full TIMEOUT_MS budget

waitRunningGetUrl and waitHttpReady are each given the full TIMEOUT_MS value independently. In the worst case the bring-up phase can block for up to 2 × TIMEOUT_MS (240 s with the default), which contradicts the stated "Timeout: 120 s" contract at the top of the file.

Suggested change

sandboxUrl = await waitRunningGetUrl(task_arn, subAgent as AgentRow, TIMEOUT_MS);

await prisma.session.update({

where: { session_id },

data: { sandbox_url: sandboxUrl, phase: "waiting_http" },

});

await waitHttpReady(sandboxUrl, TIMEOUT_MS);

const deadline = Date.now() + TIMEOUT_MS;

sandboxUrl = await waitRunningGetUrl(task_arn, subAgent as AgentRow, deadline - Date.now());

await prisma.session.update({

where: { session_id },

data: { sandbox_url: sandboxUrl, phase: "waiting_http" },

});

await waitHttpReady(sandboxUrl, deadline - Date.now());

greptile-apps · 2026-05-19T04:44:24Z

+  name: z
+    .string()
+    .min(1)
+    .max(64)
+    .regex(/^[a-zA-Z0-9_-]+$/, "name must be alphanumeric + underscores/hyphens"),
+  description: z.string().min(1).max(256),
+});
+
+const PutToolsBody = z.object({


AgentToolSpecSchema is duplicated across two files

An identical AgentToolSpecSchema definition was added here and independently in src/server/types.ts. If the two schemas drift, this copy will silently accept values that the shared layer rejects (or vice-versa). Import the schema from types.ts instead of redeclaring it.

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

ishaan-berri · 2026-05-19T22:07:56Z

@greptile review this again

greptile-apps · 2026-05-19T22:13:14Z

+  function removeEntry(i: number) {
+    onChange(value.filter((_, idx) => idx !== i));
+  }
+
+  function updateEntry(i: number, patch: Partial<AgentToolSpec>) {
+    onChange(value.map((entry, idx) => (idx === i ? { ...entry, ...patch } : entry)));
+  }


Blank entry saved to server immediately on "Add" click

addEntry calls onChange with { agent_id: "", name: "", description: "" }. The parent's onChange handler in page.tsx fires handleAgentToolsSave immediately (fire-and-forget), which sends the partial entry to the PATCH endpoint. The server parses with AgentToolSpecSchema, where "" fails both z.string().uuid() and .min(1), so every click on "Add sub-agent tool" results in a 400 error displayed to the user. The same applies on each keystroke while fields are being filled in — saves race against each other, producing a flickering error state until every field on every entry is valid simultaneously.

Copilot AI review requested due to automatic review settings May 19, 2026 04:39

Copilot AI reviewed May 19, 2026

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greptile-apps Bot reviewed May 19, 2026

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Update src/components/agent-as-tool-picker.tsx

ba3a6d2

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

greptile-apps Bot reviewed May 19, 2026

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feat(agent-as-tool): configure sub-agents as callable tools#197

feat(agent-as-tool): configure sub-agents as callable tools#197
unrealandychan wants to merge 2 commits into
BerriAI:mainfrom
unrealandychan:feat/agent-as-tool

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		const TIMEOUT_MS =
		parseInt(process.env.AGENT_TOOL_INVOKE_TIMEOUT_MS ?? "120000", 10);

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Pull request overview

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Greptile Summary

Confidence Score: 3/5

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