agents-sdk-dotnet-debugging

A troubleshooting checklist for Microsoft 365 Agents SDK applications written in C# or .NET. It checks the application from compilation and startup through authentication, networking, and an end-to-end local test.

In plain words
What is it for?
Use it to investigate build errors, startup crashes, missing ports, appsettings.json problems, Azure AD credential failures, and agents that do not respond to messages.
Why use it?
It narrows common agent failures to code, configuration, or reachability problems and checks those prerequisites in a fixed order.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/microsoft/agents/agents-sdk-dotnet-debugging
Any agent
npx skills add microsoft/Agents --skill agents-sdk-dotnet-debugging
Clone the repo
git clone --depth 1 https://github.com/microsoft/Agents

Made for: Claude Code, Codex.

Per session 136 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,348 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00136 $0.02348
Opus 5 $0.00068 $0.01174
Sonnet 5 $0.00027 $0.00470
Haiku 4.5 $0.00014 $0.00235

Measured 2d ago against content hash bfc0c8834ce1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

agents-sdk-dotnet-debugging scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl -s -o /dev/null -w "%{http_code}" \
agent-plugins/agents-for-net/skills/agents-sdk-dotnet-debugging/SKILL.md · 315 lines

How it starts

The opening of the file, as written. The whole thing — 315 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugging Agents Built with Microsoft Agents SDK (.NET)

Overview

Most agent failures fall into one of three categories: the code doesn't build or start, the configuration is wrong, or the agent isn't reachable. Work through this checklist in order — each step confirms a prerequisite for the next.

Checklist

You MUST create a task for each of these items and complete them in order:

  1. Make sure the code builds successfully.
  2. Make sure the application starts and runs without crashing.
  3. Make sure the application opens a port and listens for incoming requests.
  4. Validate the appsettings.json configuration.
  5. Validate the bot's credentials against Azure AD.
  6. Use the Agents Playground to test the agent end-to-end locally.

1. Build the code

dotnet build

Expected: exits with code 0, no errors. Fix any C# compile errors before continuing.

Common build errors:

  • Missing packagedotnet add package Microsoft.Agents.Hosting.AspNetCore
  • Namespace not found — wrong using statement; see the agents-sdk-dotnet skill for correct namespaces
  • Target framework mismatch — Agents SDK requires .NET 8+; check <TargetFramework> in .csproj

2. Start the application

Run with detailed logging:

dotnet run

Or with verbose logging:

dotnet run --verbosity detailed

To enable debug-level SDK logging, add to appsettings.Development.json:

{
  "Logging": {
    "LogLevel": {
      "Default": "Debug",
      "Microsoft.Agents": "Debug",
      "Microsoft.AspNetCore": "Warning"
    }
  }
}

Watch for crash output. Common startup errors:

  • Unable to resolve service for type 'IStorage' — missing builder.Services.AddSingleton<IStorage, MemoryStorage>() in Program.cs
  • AddAgentAspNetAuthentication missing — add builder.Services.AddAgentAspNetAuthentication(builder.Configuration)
  • Port already in use — another process is on the port; check with netstat -ano | findstr :3978 (Windows) or lsof -i :3978 (macOS/Linux)
  • InvalidOperationException on startup — check appsettings.json structure, especially Connections and ConnectionsMap

Read the full file on GitHub · 315 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 315 lines · 136 tokens per session scan A bfc0c8834ce1

Subscribe to this mod's changes

agents-sdk-dotnet-debugging is a skill published in the GitHub repository microsoft/Agents (1,050 stars, last pushed 5d ago), licensed MIT. It adds 136 tokens to every session and 2,348 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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