3064a73 Implement MCP server instructions handling: append instructions to system prompt in chat payload and add configuration option in AddToolServerModal.
Note to first-time contributors: Please open a discussion post in Discussions to discuss your idea/fix with the community before creating a pull request, and describe your changes before submitting a pull request.
This is to ensure large feature PRs are discussed with the community first, before starting work on it. If the community does not want this feature or it is not relevant for Open WebUI as a project, it can be identified in the discussion before working on the feature and submitting the PR.
Before submitting, make sure you've checked the following:
Target branch: Verify that the pull request targets the dev branch. PRs targeting main will be immediately closed.
Description: Provide a concise description of the changes made in this pull request down below.
Changelog: Ensure a changelog entry following the format of Keep a Changelog is added at the bottom of the PR description.
Documentation: Add docs in Open WebUI Docs Repository. Document user-facing behavior, environment variables, public APIs/interfaces, or deployment steps.
Dependencies: Are there any new or upgraded dependencies? If so, explain why, update the changelog/docs, and include any compatibility notes. Actually run the code/function that uses updated library to ensure it doesn't crash.
Testing: Perform manual tests to verify the implemented fix/feature works as intended AND does not break any other functionality. Include reproducible steps to demonstrate the issue before the fix. Test edge cases (URL encoding, HTML entities, types). Take this as an opportunity to make screenshots of the feature/fix and include them in the PR description.
Agentic AI Code: Confirm this Pull Request is not written by any AI Agent or has at least gone through additional human review AND manual testing. If any AI Agent is the co-author of this PR, it may lead to immediate closure of the PR.
Code review: Have you performed a self-review of your code, addressing any coding standard issues and ensuring adherence to the project's coding standards?
Design & Architecture: Prefer smart defaults over adding new settings; use local state for ephemeral UI logic. Open a Discussion for major architectural or UX changes.
Git Hygiene: Keep PRs atomic (one logical change). Clean up commits and rebase on dev to ensure no unrelated commits (e.g. from main) are included. Push updates to the existing PR branch instead of closing and reopening.
Title Prefix: To clearly categorize this pull request, prefix the pull request title using one of the following:
feat: Introduces a new feature or enhancement to the codebase
Changelog Entry
Description
When an admin-configured MCP tool server is used in a chat, Open WebUI now captures optional instructions from the MCP initialize response (InitializeResult.instructions) and appends them to the system message in the chat payload (same pattern as other system-prompt injections). This lets MCP servers document how models should use their tools without duplicating everything in per-tool descriptions.
Per-connection opt-out is available via config.forward_mcp_instructions (default true when omitted). The admin Add/Edit Connection modal (MCP) exposes this under Advanced as “Include MCP server instructions” with a tooltip explaining behavior; import/export JSON includes the flag for MCP connections.
Added
Forwarding of MCP server initializeinstructions into the chat system prompt when the server is connected for a request and forwarding is enabled.
Admin UI: MCP-only control under Advanced in AddToolServerModal.svelte (label + switch + tooltip); wired through save/load/import/export for MCP connections.
Changed
MCPClient stores server_instructions from the post-initialize result and clears it on disconnect.
Security
Admins should be aware that MCP servers control the instructions string; disabling forwarding (forward_mcp_instructions: false) avoids injecting server-provided text into the model context.
Breaking Changes
BREAKING CHANGE: None. Existing behavior is preserved when forward_mcp_instructions is omitted (treated as true).
Additional Information
Files (high level):backend/open_webui/utils/mcp/client.py (read InitializeResult.instructions), backend/open_webui/utils/middleware.py (append via add_or_update_system_message when enabled), src/lib/components/AddToolServerModal.svelte (UI + config.forward_mcp_instructions).
Dependencies: None added or upgraded; uses the existing Python mcp SDK types that already include InitializeResult.instructions.
Docs: A short note in the Open WebUI docs (MCP / tool servers) describing forward_mcp_instructions and the UI toggle would help operators; link the docs PR here when opened.
Screenshots or Videos
Contributor License Agreement
By submitting this pull request, I confirm that I have read and fully agree to the Contributor License Agreement (CLA), and I am providing my contributions under its terms.
Note
Deleting the CLA section will lead to immediate closure of your PR and it will not be merged in.
🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.
## 📋 Pull Request Information
**Original PR:** https://github.com/open-webui/open-webui/pull/23458
**Author:** [@jmleksan](https://github.com/jmleksan)
**Created:** 4/6/2026
**Status:** 🔄 Open
**Base:** `dev` ← **Head:** `feat/MCP-instructions`
---
### 📝 Commits (2)
- [`3064a73`](https://github.com/open-webui/open-webui/commit/3064a73f1668d34281ffe795ba3bbbf799882857) Implement MCP server instructions handling: append instructions to system prompt in chat payload and add configuration option in AddToolServerModal.
- [`4f12b14`](https://github.com/open-webui/open-webui/commit/4f12b14e9ad5cdf52074690c737e3369b1e903e4) fix review notes
### 📊 Changes
**3 files changed** (+67 additions, -5 deletions)
<details>
<summary>View changed files</summary>
📝 `backend/open_webui/utils/mcp/client.py` (+8 -1)
📝 `backend/open_webui/utils/middleware.py` (+19 -0)
📝 `src/lib/components/AddToolServerModal.svelte` (+40 -4)
</details>
### 📄 Description
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# Pull Request Checklist
### Note to first-time contributors: Please open a discussion post in [Discussions](https://github.com/open-webui/open-webui/discussions) to discuss your idea/fix with the community before creating a pull request, and describe your changes before submitting a pull request.
This is to ensure large feature PRs are discussed with the community first, before starting work on it. If the community does not want this feature or it is not relevant for Open WebUI as a project, it can be identified in the discussion before working on the feature and submitting the PR.
**Before submitting, make sure you've checked the following:**
- [x] **Target branch:** Verify that the pull request targets the `dev` branch. **PRs targeting `main` will be immediately closed.**
- [x] **Description:** Provide a concise description of the changes made in this pull request down below.
- [x] **Changelog:** Ensure a changelog entry following the format of [Keep a Changelog](https://keepachangelog.com/) is added at the bottom of the PR description.
- [x] **Documentation:** Add docs in [Open WebUI Docs Repository](https://github.com/open-webui/docs). Document user-facing behavior, environment variables, public APIs/interfaces, or deployment steps.
- [x] **Dependencies:** Are there any new or upgraded dependencies? If so, explain why, update the changelog/docs, and include any compatibility notes. Actually run the code/function that uses updated library to ensure it doesn't crash.
- [x] **Testing:** Perform manual tests to **verify the implemented fix/feature works as intended AND does not break any other functionality**. Include reproducible steps to demonstrate the issue before the fix. Test edge cases (URL encoding, HTML entities, types). Take this as an opportunity to **make screenshots of the feature/fix and include them in the PR description**.
- [x] **Agentic AI Code:** Confirm this Pull Request is **not written by any AI Agent** or has at least **gone through additional human review AND manual testing**. If any AI Agent is the co-author of this PR, it may lead to immediate closure of the PR.
- [x] **Code review:** Have you performed a self-review of your code, addressing any coding standard issues and ensuring adherence to the project's coding standards?
- [x] **Design & Architecture:** Prefer smart defaults over adding new settings; use local state for ephemeral UI logic. Open a Discussion for major architectural or UX changes.
- [x] **Git Hygiene:** Keep PRs atomic (one logical change). Clean up commits and rebase on `dev` to ensure no unrelated commits (e.g. from `main`) are included. Push updates to the existing PR branch instead of closing and reopening.
- [x] **Title Prefix:** To clearly categorize this pull request, prefix the pull request title using one of the following:
- **feat**: Introduces a new feature or enhancement to the codebase
# Changelog Entry
### Description
When an admin-configured MCP tool server is used in a chat, Open WebUI now captures optional **`instructions`** from the MCP **`initialize`** response (`InitializeResult.instructions`) and appends them to the **system** message in the chat payload (same pattern as other system-prompt injections). This lets MCP servers document how models should use their tools without duplicating everything in per-tool descriptions.
Per-connection opt-out is available via **`config.forward_mcp_instructions`** (default **true** when omitted). The admin **Add/Edit Connection** modal (MCP) exposes this under **Advanced** as **“Include MCP server instructions”** with a tooltip explaining behavior; import/export JSON includes the flag for MCP connections.
### Added
- Forwarding of MCP server **`initialize`** **`instructions`** into the chat system prompt when the server is connected for a request and forwarding is enabled.
- Connection config key **`forward_mcp_instructions`** (boolean; default **true**).
- Admin UI: MCP-only control under **Advanced** in `AddToolServerModal.svelte` (label + switch + tooltip); wired through save/load/import/export for MCP connections.
### Changed
- `MCPClient` stores `server_instructions` from the post-`initialize` result and clears it on disconnect.
### Security
- Admins should be aware that MCP servers control the **`instructions`** string; disabling forwarding (`forward_mcp_instructions: false`) avoids injecting server-provided text into the model context.
### Breaking Changes
- **BREAKING CHANGE:** None. Existing behavior is preserved when **`forward_mcp_instructions`** is omitted (treated as **true**).
---
### Additional Information
- **Files (high level):** `backend/open_webui/utils/mcp/client.py` (read `InitializeResult.instructions`), `backend/open_webui/utils/middleware.py` (append via `add_or_update_system_message` when enabled), `src/lib/components/AddToolServerModal.svelte` (UI + `config.forward_mcp_instructions`).
- **Dependencies:** None added or upgraded; uses the existing Python **`mcp`** SDK types that already include `InitializeResult.instructions`.
- **Docs:** A short note in the Open WebUI docs (MCP / tool servers) describing **`forward_mcp_instructions`** and the UI toggle would help operators; link the docs PR here when opened.
### Screenshots or Videos
<img width="495" height="633" alt="image" src="https://github.com/user-attachments/assets/d915800c-2082-4c08-90d0-4cbdb6e2b75d" />
### Contributor License Agreement
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Deleting it will trigger the CLA-Bot to INVALIDATE your PR.
Your PR will NOT be reviewed or merged until you check the box below confirming that you have read and agree to the terms of the CLA.
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- [x] By submitting this pull request, I confirm that I have read and fully agree to the [Contributor License Agreement (CLA)](https://github.com/open-webui/open-webui/blob/main/CONTRIBUTOR_LICENSE_AGREEMENT), and I am providing my contributions under its terms.
> [!NOTE]
> Deleting the CLA section will lead to immediate closure of your PR and it will not be merged in.
---
<sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>
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📋 Pull Request Information
Original PR: https://github.com/open-webui/open-webui/pull/23458
Author: @jmleksan
Created: 4/6/2026
Status: 🔄 Open
Base:
dev← Head:feat/MCP-instructions📝 Commits (2)
3064a73Implement MCP server instructions handling: append instructions to system prompt in chat payload and add configuration option in AddToolServerModal.4f12b14fix review notes📊 Changes
3 files changed (+67 additions, -5 deletions)
View changed files
📝
backend/open_webui/utils/mcp/client.py(+8 -1)📝
backend/open_webui/utils/middleware.py(+19 -0)📝
src/lib/components/AddToolServerModal.svelte(+40 -4)📄 Description
Pull Request Checklist
Note to first-time contributors: Please open a discussion post in Discussions to discuss your idea/fix with the community before creating a pull request, and describe your changes before submitting a pull request.
This is to ensure large feature PRs are discussed with the community first, before starting work on it. If the community does not want this feature or it is not relevant for Open WebUI as a project, it can be identified in the discussion before working on the feature and submitting the PR.
Before submitting, make sure you've checked the following:
devbranch. PRs targetingmainwill be immediately closed.devto ensure no unrelated commits (e.g. frommain) are included. Push updates to the existing PR branch instead of closing and reopening.Changelog Entry
Description
When an admin-configured MCP tool server is used in a chat, Open WebUI now captures optional
instructionsfrom the MCPinitializeresponse (InitializeResult.instructions) and appends them to the system message in the chat payload (same pattern as other system-prompt injections). This lets MCP servers document how models should use their tools without duplicating everything in per-tool descriptions.Per-connection opt-out is available via
config.forward_mcp_instructions(default true when omitted). The admin Add/Edit Connection modal (MCP) exposes this under Advanced as “Include MCP server instructions” with a tooltip explaining behavior; import/export JSON includes the flag for MCP connections.Added
initializeinstructionsinto the chat system prompt when the server is connected for a request and forwarding is enabled.forward_mcp_instructions(boolean; default true).AddToolServerModal.svelte(label + switch + tooltip); wired through save/load/import/export for MCP connections.Changed
MCPClientstoresserver_instructionsfrom the post-initializeresult and clears it on disconnect.Security
instructionsstring; disabling forwarding (forward_mcp_instructions: false) avoids injecting server-provided text into the model context.Breaking Changes
forward_mcp_instructionsis omitted (treated as true).Additional Information
backend/open_webui/utils/mcp/client.py(readInitializeResult.instructions),backend/open_webui/utils/middleware.py(append viaadd_or_update_system_messagewhen enabled),src/lib/components/AddToolServerModal.svelte(UI +config.forward_mcp_instructions).mcpSDK types that already includeInitializeResult.instructions.forward_mcp_instructionsand the UI toggle would help operators; link the docs PR here when opened.Screenshots or Videos
Contributor License Agreement
🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.