[BUG] Recursion limit reached with flat agent tool list

[Daniel-Vaz]

📋 Prerequisites

• I have searched the existing issues to avoid creating a duplicate
• By submitting this issue, you agree to follow our Code of Conduct
• I am using the latest version of the software
• I have tried to clear cache/cookies or used incognito mode (if ui-related)
• I can consistently reproduce this issue

🎯 Affected Service(s)

Controller Service

🚦 Impact/Severity

Blocker

🐛 Bug Description

When a declarative agent references multiple other agents as tools (e.g., 11 agent tools), validation fails with “recursion limit reached in agent tool chain” even though the tool agents only use MCP tools (no further agent tools). The expected nesting depth is 1 (main → tool agent), far below the MAX_DEPTH=10.

🔄 Steps To Reproduce

1. Create a agent that calls other agents:

apiVersion: kagent.dev/v1alpha2
kind: Agent
metadata:
  name: main-agent
spec:
  description: "(...)"
  type: Declarative
  declarative:
    modelConfig: default-model-config
    systemMessage: |
      (...)
    tools:
    - type: Agent
      agent:
        name: sub-agent-1
    - type: Agent
      agent:
        name: sub-agent-2
    - type: Agent
      agent:
        name: sub-agent-3
    - type: Agent
      agent:
        name: sub-agent-4
    - type: Agent
      agent:
        name: sub-agent-5
    - type: Agent
      agent:
        name: sub-agent-6
    - type: Agent
      agent:
        name: sub-agent-7
    - type: Agent
      agent:
        name: sub-agent-8
    - type: Agent
      agent:
        name: sub-agent-9
    - type: Agent
      agent:
        name: sub-agent-10
    - type: Agent
      agent:
        name: sub-agent-11

2. Then make sure those sub-agents have tools, but only mcpServer tools and not agents:

apiVersion: kagent.dev/v1alpha2
kind: Agent
metadata:
  name: sub-agent-X
spec:
  description: "(...)"
  type: Declarative
  declarative:
    a2aConfig:
      skills:
        (...)
    modelConfig: default-model-config
    systemMessage: |
      (...)
    tools:
    - type: McpServer
      mcpServer:
        apiGroup: kagent.dev
        kind: RemoteMCPServer
        name: grafana-mcpserver
        toolNames:
        - list_prometheus_metric_names
        - list_prometheus_metric_metadata
        - list_prometheus_label_names
        - list_prometheus_label_values

3. Validate the state of the main agent:

$ kubectl describe agents.kagent.dev main-agent

(...)
Status:
  Conditions:
    Message:               failed to translate agent default/main-agent: recursion limit reached in agent tool chain: default/sub-agent-11 -> default/sub-agent-11

🤔 Expected Behavior

Since Sub agents aren't calling any other agents, I expect that the main agent can still be created without problems.

📱 Actual Behavior

The main agent fails to be accepted by the controller.

💻 Environment

Component	Version / Details
kagent	0.7.13
Kubernetes	kubeadm v1.34.3
Cloud / Infra	Self-managed k8s cluster
LLM provider	Azure OpenAI
Model	gpt-5-mini
MCP Servers Used	kagent-tools + Grafana MCP Server
Grafana MCP Server	0.9.0
Agent topology	Main Agent → Sub-agent → MCP tools

🔧 CLI Bug Report

No response

🔍 Additional Context

No response

📋 Logs

{"level":"error","ts":"2026-02-12T08:27:50Z","logger":"reconciler","msg":"failed to reconcile agent","agent":{"name":"main-agent","namespace":"default"},"error":"failed to translate agent default/main-agent: recursion limit reached in agent tool chain: default/sub-agent-11 -> default/sub-agent-11","stacktrace":"github.com/kagent-dev/kagent/go/internal/controller/reconciler.(*kagentReconciler).ReconcileKagentAgent\n\t/workspace/internal/controller/reconciler/reconciler.go:93\ngithub.com/kagent-dev/kagent/go/internal/controller.(*AgentController).Reconcile\n\t/workspace/internal/controller/agent_controller.go:64\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Reconcile\n\t/root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.23.0/pkg/internal/controller/controller.go:222\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).reconcileHandler\n\t/root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.23.0/pkg/internal/controller/controller.go:479\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).processNextWorkItem\n\t/root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.23.0/pkg/internal/controller/controller.go:438\nsigs.k8s.io/controller-runtime/pkg/internal/controller.(*Controller[...]).Start.func1.1\n\t/root/go/pkg/mod/sigs.k8s.io/controller-runtime@v0.23.0/pkg/internal/controller/controller.go:313"}

📷 Screenshots

No response

🙋 Are you willing to contribute?

• I am willing to submit a PR to fix this issue

[opspawn]

I've submitted a fix for this in #1288 — it corrects the recursion depth tracking by using copy-on-write state in the with() method. The flat tool list bug described here is now properly handled (siblings no longer increment each other's depth counter). Would appreciate a review when you get a chance.

[Daniel-Vaz]

Tested it and it's working.
Thank you very much.