Microsoft 365 Agents SDK is a C# and .NET software development kit for building agents that interact with users across Microsoft 365, Teams, Copilot Studio, Webchat, and selected third-party services. Developers use it to handle conversations, coordinate requests, generate responses, and enable collaboration between agents. The catalogue entries provide coding-agent instructions and agents for working with this SDK.
Borrowing it
Nothing to install: this file belongs to microsoft/Agents-for-net. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/microsoft/Agents-for-net/main/.github/instructions/proactive-messaging.instructions.mdgit clone --depth 1 https://github.com/microsoft/Agents-for-netWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/instructions/microsoft/agents-for-net/proactive-messaging)<a href="https://agentmods.dev/instructions/microsoft/agents-for-net/proactive-messaging"><img src="https://agentmods.dev/badge/instructions/microsoft/agents-for-net/proactive-messaging/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/instructions/microsoft/agents-for-net/proactive-messaging"><img src="https://agentmods.dev/badge/instructions/microsoft/agents-for-net/proactive-messaging.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00791 | $0.00791 |
| Opus 5.5 | $0.00316 | $0.00316 |
| Sonnet 5.5 | $0.00158 | $0.00158 |
| Haiku 4.5 | $0.00079 | $0.00079 |
Grade A, and why
Agents-for-net proactive-messaging.instructions.md scanned grade A with 0 findings 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 27d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 47 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Proactive Messaging Context
When working on proactive messaging, conversation continuation, or proactive HTTP endpoints, read docs/proactive-sequence-diagram.md for the full mermaid sequence diagrams covering all flows.
Key Design Points
- Conversation storage is required for
{conversationId}HTTP routes, which resolve the target fromIStorage. Body-based HTTP routes and in-code overloads can receive a completeConversationdirectly.Proactive.StoreConversationAsyncpersistsConversation(Claims + ConversationReference) under keyproactive/conversations/{conversationId}. - Two invocation styles: HTTP endpoints (via
MapAgentProactiveEndpoints) for external triggers, and in-codeProactive.ContinueConversationAsync/Proactive.SendActivityAsyncfor agent-initiated scenarios. - SendActivity is fire-and-send — it creates a minimal turn to deliver a single activity. ContinueConversation creates a full turn with TurnState, middleware, and optional token handling.
- ProcessProactiveAsync on the adapter creates the full turn pipeline (state, middleware). This differs from the simpler
ContinueConversationAsyncon the adapter which only provides a raw TurnContext callback. - Exception handling — Exceptions inside proactive callbacks are captured via
ExceptionDispatchInfoand re-thrown after the adapter call completes. Without this, exceptions in the background pipeline would be silently lost. - Token handling —
[ContinueConversation(autoSignInHandlers: "me")]attribute triggers automatic token acquisition during proactive turns. IfProactiveOptions.FailOnUnsignedInConnectionsis true (default),UserNotSignedInis thrown when tokens cannot be acquired. - HTTP query parameters are passed through as
Activity.Value(dictionary) withValueType = "application/vnd.microsoft.activity.continueconversation+json"on the continuation Event activity. - CreateConversation creates a new conversation on the channel (e.g., 1:1 in Teams) and optionally stores it and/or continues into it.
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.
- 27d ago Changed · +22 tokens per session 0cda6b170150
- 2mo ago First seen · 47 lines · 769 tokens per session scan A 53fb1646fde7
Agents-for-net proactive-messaging.instructions.md is an instructions file published in the GitHub repository microsoft/Agents-for-net (183 stars, last pushed today), licensed MIT. It adds 791 tokens to every session, about $0.0032 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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AGENTS.md instructions for vercel/next.js, covering next.js development guide, codebase structure, monorepo overview, core package: packages/next and other important packages.
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AGENTS.md instructions for langchain-ai/langchain, covering global development guidelines for the langchain monorepo, corridor security analysis, project architecture and context, monorepo structure and development tools & commands.
vscode copilot-instructions.md
Copilot instructions for microsoft/vscode, covering vs code copilot instructions, project overview, root folders, core architecture (src/ folder) and built-in extensions (extensions/ folder).
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AGENTS.md instructions for deepseek-ai/deepseek-harness, covering agents.md, pre-stable apis and released session data, repository layout, commands and host sandbox failures.