Bruno MCP Server

🔌 Bruno MCP Server for Python

Python MCP server for running Bruno collections. It exposes a Model Context Protocol server over stdio with tools that run collections through the bru CLI and return normalized JSON results.

Note: All examples in this repository use placeholder names (project1, /home/user/project/bruno, example.test). Replace them with your own paths and collection names.

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✨ Features

• Run Bruno collections natively using the Bruno CLI.
• Discover collections and sibling environment files automatically.
• Support environment files and dynamic environment variables.
• Secure Secret Injection: Pass secrets to Bruno without exposing values to the LLM via inherited_variables. Secret values are injected through a temporary, owner-only --env-file and the child process environment — they never appear in CLI arguments (ps output) or logs.
• Filter Inspection: Inspect documented query filters and run temporary filter scenarios without modifying the source collection.
• Two-Phase Full Validation: Execute baseline tests + all documented filters in a single tool call.
• Normalized Outputs: Return structured execution results containing success, summary, failures, and timings.

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📦 Requirements

• Python: 3.10 or newer
• Package Manager: uv
• Node Package Manager: npm (only if the Bruno CLI is not already installed)

The installer checks whether the Bruno CLI command bru is available. If it is missing, the server fails with an explicit error instead of silently installing packages. To install the pinned version manually:

npm install -g @usebruno/cli@4.2.0

Runtime auto-install is available but opt-in: set BRUNO_MCP_AUTO_INSTALL_BRU=1 (or auto_install = true under [bruno] in the config file) and the server installs exactly the pinned version from cli_version / BRUNO_MCP_BRU_VERSION.

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🚀 Installation & Running

1. Installation

Install dependencies using uv:

uv sync

(If your configured package index does not mirror the MCP Python SDK, point uv at PyPI for the sync: UV_DEFAULT_INDEX=https://pypi.org/simple uv sync)

2. Running the Server

You can run the server directly using uv:

uv run bruno-mcp

Alternatively, run the module directly inside the uv environment: uv run python -m bruno_mcp

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⚙️ Configuration

MCP Configuration

Example MCP stdio configuration from this workspace root:

{
  "mcpServers": {
    "bruno-runner": {
      "command": "uv",
      "args": ["run", "bruno-mcp"]
    }
  }
}

Configuration File (bruno-mcp.toml)

Default roots and auth aliases can be configured in bruno-mcp.toml in the current working directory, or globally in ~/.config/bruno-mcp/config.toml.

See bruno-mcp.example.toml for a commented template:

[workspace]
roots = [
  "/home/user/project/bruno"
]

[bruno]
cli_version = "4.2.0"   # pinned Bruno CLI version
auto_install = false     # never install bru silently at runtime

[limits]
run_timeout_seconds = 300
max_output_bytes = 8388608
max_concurrent_runs = 2

[artifacts]
ttl_hours = 24           # raw reports are auto-deleted after this
max_files = 50

[security]
enforce_root_confinement = true   # reject collection paths outside workspace roots

[auth]
inherited_variables = [
  "BRUNO_AUTH_TOKEN",
  "BRUNO_API_KEY"
]

[defaults]
environment = "dev"

Every setting can also be set via environment variables (BRUNO_MCP_BRU_VERSION, BRUNO_MCP_AUTO_INSTALL_BRU, BRUNO_MCP_RUN_TIMEOUT, BRUNO_MCP_MAX_OUTPUT_BYTES, BRUNO_MCP_MAX_CONCURRENT_RUNS, BRUNO_MCP_ARTIFACTS_DIR, BRUNO_MCP_ARTIFACT_TTL_HOURS, BRUNO_MCP_ARTIFACT_MAX_FILES, BRUNO_MCP_ENFORCE_ROOT_CONFINEMENT, BRUNO_MCP_LOG_LEVEL), which take precedence over the file.

Note: The installer creates ~/.config/bruno-mcp/config.toml with a dummy root. Local bruno-mcp.toml files are git-ignored so real paths and environment names are never committed.

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💻 Local VS Code Installation

From the project root, install dependencies with uv:

UV_DEFAULT_INDEX=[https://pypi.org/simple](https://pypi.org/simple) uv sync

Ensure the Bruno CLI is available (bru --version). This repository includes .vscode/mcp.json, allowing VS Code to discover the local MCP server from the workspace:

{
  "servers": {
    "bruno-runner": {
      "type": "stdio",
      "command": "uv",
      "args": ["run", "bruno-mcp"]
    }
  }
}

Reload the VS Code window after syncing dependencies. The bruno-runner server should now be available in the MCP servers list.

Global Installation

To install the MCP server in the VS Code user profile so it is available from any workspace:

uv run python scripts/install_vscode.py

(To also install the reusable Copilot prompt and agent globally, append --with-copilot-customizations to the command above).

To install it manually in another local VS Code workspace, change the command args to include --directory:

"args": ["--directory", "/home/user/mcp-bruno", "run", "bruno-mcp"]

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🧰 Available Tools

🔍 list-collections

Lists Bruno collections below a root directory or configured roots. Use it when the user provides a partial collection name instead of a full path.

• root (optional): Bruno root directory (usually contains collections/ and environments/).
• query (optional): Case-insensitive text used to filter collection names and paths.

▶️ run-collection

Runs a Bruno collection and returns normalized execution results.

• collection (required): Path to the Bruno collection.
• environment (optional): Path to an environment file.
• variables (optional): Environment variables as KEY=value strings.
• inherited_variables (optional): Names of environment variables to read from the MCP server process and inject into Bruno without exposing values to the LLM. Values travel via a temporary owner-only --env-file and the child process environment ({{process.env.NAME}} also works) — never in CLI arguments.

Auth Handling: For secrets, prefer inherited_variables instead of writing values in chat. By default, the secure MCP input BRUNO_AUTH_TOKEN can satisfy Bruno variables named bearerToken, BEARER_TOKEN, AUTH_TOKEN, TOKEN, accessToken, or access_token. Secrets are injected via a temporary private --env-file; if the selected --env environment file declares the same variable (which would take precedence inside bru), the run transparently switches to a temporary sanitized copy of the collection with the conflicting entry removed, so the injected secret always wins and source files are never modified.

Workspace confinement: When [workspace] roots are configured (and at least one exists on disk), collection paths outside those roots are rejected with a clear error. Set enforce_root_confinement = false to disable.

Execution limits: Each bru run has a configurable timeout (run_timeout_seconds, default 300s), bounded stdout/stderr capture (max_output_bytes), and a concurrency cap (max_concurrent_runs). Raw JSON reports are stored as artifacts with owner-only (0600) permissions and expire automatically (ttl_hours / max_files). Structured logs go to stderr (BRUNO_MCP_LOG_LEVEL).

Supported Collection Inputs:

• Collection directory: /path/to/bruno/collections/project1
• Bruno request file: /path/to/bruno/collections/project1/request.bru
• Internal .vru request file: /path/to/bruno/collections/project1/request.vru
• Open collection descriptor: /path/to/bruno/collections/project1/opencollection.yml

When Bruno failures look like authentication problems, the response includes auth_failure: true and an auth_message.

Example with inherited secrets:

{
  "collection": "/home/user/project/bruno/collections/project1",
  "environment": "dev",
  "inherited_variables": ["BRUNO_AUTH_TOKEN"]
}

🌍 discover-environments

Inspects the folder structure around a Bruno collection and returns the sibling environments directory, available environment names, and variable names (without returning secret values).

📖 read-result-artifact

Reads a bounded, redacted summary from the raw Bruno JSON artifact path returned by run-collection.

• path (required): The artifact.path value returned by a previous run.
• max_items (optional): Number of response items to sample per request (default 3, max 20).

🧪 list-request-filters & run-filter-scenarios

• list-request-filters: Inspects YAML request files and returns query params split into enabled and disabled groups.
• run-filter-scenarios: Runs temporary request variants with selected disabled query params enabled without modifying the source files.

🛡️ run-full-validation

Two-phase orchestration in a single tool call:

1. Baseline: Runs the collection once and checks every endpoint responds without errors (no 4xx/5xx).
2. Filters: Only runs if the baseline is green. Automatically discovers and tests every disabled query filter across every endpoint.

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🤖 Prompt and Agent Automation

The project includes reusable Copilot prompt and agent templates:

• Prompt template: copilot/prompts/run-bruno-collection.prompt.md
• Agent template: copilot/agents/bruno-runner.agent.md

Install them globally with:

uv run python scripts/install_vscode.py --with-copilot-customizations

The agent will seamlessly navigate the workspace, discover collections/environments, handle credentials securely via inherited_variables, and return detailed execution summaries:

{
  "success": true,
  "summary": {
    "total": 5,
    "failed": 0,
    "passed": 5
  },
  "failures": [],
  "auth_failure": false,
  "auth_message": null,
  "timings": {
    "started": "2024-03-14T10:00:00.000000Z",
    "completed": "2024-03-14T10:00:01.000000Z",
    "duration": 1000
  }
}

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🐳 Docker

The Docker image installs both this Python server and the Bruno CLI:

docker build -t bruno-mcp-python .
docker run --rm -i bruno-mcp-python

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🛠️ Development & Project Structure

Commands:

• Compile-check the sources: uv run python -m compileall src
• Run the test suite: uv run python -m unittest discover -s tests -v

Structure:

.
├── src/bruno_mcp/         # MCP server, runner, config, and types
├── scripts/               # VS Code installer script
├── copilot/               # Reusable Copilot prompt and agent templates
├── tests/                 # Unit tests
├── .vscode/mcp.json       # Workspace MCP server entry
└── bruno-mcp.example.toml # Commented configuration template

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mcp-name: io.github.kta41/mcp-bruno

📄 License

Released under the MIT License.