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URLs sometimes disappear in Copilot responses when using a declarative agent with API plugin

Clara 0 Reputation points
2025-10-08T07:00:18.4733333+00:00

We’re experiencing an issue with a declarative agent that uses an API plugin.

In a regular agent chat, the responses generated by the agent correctly include URLs, and they are displayed as expected. However, when the same agent is mentioned in Microsoft 365 Copilot using an @mention, the URLs sometimes disappear from the final response displayed in the chat window.

Has anyone encountered this issue before? Is there a known reason why URLs might be removed or hidden in this context and if so, how can this be prevented or fixed?

Thanks in advance for any insights!

PS: We intentionally chose not to display URLs using Adaptive Cards, so this behavior is not related to card rendering.

Microsoft Teams | Development
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  1. Karan Shewale 1,705 Reputation points Microsoft External Staff
    2025-10-08T11:55:18.5233333+00:00

    Hi Clara, Sometimes, when you use a declarative agent with an API plugin, URLs show up fine in normal chats but disappear when the agent is called using @mention in Microsoft 365 Copilot. This happens because Copilot adds extra formatting and can hide links that aren’t clearly marked. To fix this, always format URLs as clickable links using Markdown [Link Text](https://example.com) or <https://example.com>. Also, check that the agent is published correctly and assigned to the right channels. Turning on developer mode (-developer on) can help see if the URLs are being generated but not shown.

    Relevant Official Documents:

    Thank you .

    Karan Shewale.

    If this response resolves your issue, please Accept the answer and, if helpful, click the “Upvote” button. Your feedback helps us improve and assist others more effectively.

    1 person found this answer helpful.

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  1. Steven-N 11,540 Reputation points Microsoft External Staff Moderator
    2025-10-08T11:05:55.4066667+00:00

    Hi Clara

    Thank you for reaching out to Microsoft Q&A forum

    From what you have described, I understand that the problem you are facing is one in which URLs created by a declarative agent using an API plugin show up fine inside normal agent chats but at times vanish when the same agent is called using @mention inside Microsoft 365 Copilot. 

    It has been seen in other implementations and more often than not, it comes down to how Microsoft 365 Copilot renders in varying contexts of invocation. If an agent is invoked via @mention, then the response might undergo further formatting or sanitization layers which end up suppressing certain elements-most notably URLs that are not explicitly formatted.

    Moreover, declarative agents built in Copilot Studio may also return inconsistent behaviors based on how links are introduced (pasted vs. selected from the UI) and whether a set of instructions for the agent clearly defines how URLs should be presented. Such inconsistencies fall squarely within known limitations with the present extensibility framework.

    User's image Link reference: https://free.blessedness.top/en-us/microsoft-365-copilot/extensibility/known-issues

    That said, if you're noticing that URLs aren't showing up clearly in agent responses triggered via @mention in Microsoft 365 Copilot, here are a few thoughtful steps you can take to improve visibility and consistency:

    • Use clear formatting. When including URLs in the agent’s response instructions, try formatting them explicitly using Markdown
    • Avoid pasting links directly into prompts. Instead, consider selecting URLs through the Copilot Studio UI.
    • Check in developer mode. You can turn on developer mode in Copilot Chat (using -developer on) to confirm whether the URL was generated behind the scenes but simply not rendered in the visible response.
    • Review agent configuration. Make sure the agent is correctly published and assigned to the right channels. A misconfigured channel can affect how responses appear or whether certain elements (like links) are displayed at all.

    Link references:

    https://techcommunity.microsoft.com/discussions/microsoft365copilot/agent-not-visible-in-m365-copilot/4354983

    https://free.blessedness.top/en-us/microsoft-365-copilot/extensibility/declarative-agent-instructions

    Hope my answer will help you, for any further concern, kindly let me know in the comment section

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