feat: add support for Gemini CLI integration by jackwotherspoon · Pull Request #1709 · PrefectHQ/fastmcp

jackwotherspoon · 2025-09-02T00:48:26Z

Gemini CLI 🤝 FastMCP

Description

This adds support for Gemini CLI as an AI assistant integration to FastMCP via fastmcp install gemini-cli.

Gemini CLI now has support for gemini mcp add commands which has enabled this integration.

fastmcp_gemini_cli.mp4

Contributors Checklist

My change is related to issue Add support for Gemini CLI integration #1708
I have followed the repository's development workflow
I have tested my changes manually and by adding relevant tests
I have performed all required documentation updates

Review Checklist

I have self-reviewed my changes
My Pull Request is ready for review

strawgate · 2025-09-02T01:20:02Z

This looks great, I'm a big Gemini user -- I'll give this a shot tomorrow and report back!

jackwotherspoon · 2025-09-05T03:49:13Z

This looks great, I'm a big Gemini user -- I'll give this a shot tomorrow and report back!

@strawgate let me know if you run into any issues 😄

strawgate · 2025-09-05T12:59:30Z

Sorry, will try to find time today or by Monday at the latest

strawgate · 2025-09-06T14:38:51Z

Looks great; the only problem I ran into is not a problem with the Gemini CLI install command in particular but with the uv environment command building.

In UVEnvironment:

    def build_command(self, command: list[str]) -> list[str]:
        """Build complete uv run command with environment args and command to execute.

        Args:
            command: Command to execute (e.g., ["fastmcp", "run", "server.py"])

        Returns:
            Complete command ready for subprocess.run, including "uv" prefix if needed.
            If no environment configuration is set, returns the command unchanged.
        """
        # If no environment setup is needed, return command as-is
        if not self._needs_setup():
            return command

If it's determined it doesnt need setup, then the command becomes:

    "test-server": {
      "command": "fastmcp",
      "args": [
        "run",
        "/Users/bill.easton/repos/fastmcp/server.py"
      ]
    }

I don't have fastmcp in my path and so direct invocation doesn't work for me and requires uv run for it to work on my system. @jlowin perhaps we should add a check related to this?

strawgate

Small cleanup on the doc, otherwise looks good

Copilot

Pull Request Overview

This PR adds support for Gemini CLI as an AI assistant integration to FastMCP, enabling users to install FastMCP servers directly into Gemini CLI using fastmcp install gemini-cli. The integration leverages Gemini CLI's recently added MCP support via the gemini mcp add command.

Key changes:

New Gemini CLI integration module with command discovery and installation logic
Comprehensive test coverage for the new integration command
Complete documentation for the Gemini CLI integration

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/fastmcp/cli/install/gemini_cli.py	Core implementation of Gemini CLI integration with command discovery, validation, and MCP server installation
src/fastmcp/cli/install/init.py	Registration of the new gemini-cli command in the install app
tests/cli/test_install.py	Test cases covering command parsing, options handling, and integration with existing test patterns
docs/integrations/gemini-cli.mdx	User documentation explaining installation methods, configuration options, and usage examples

Copilot · 2025-09-06T14:45:43Z

+def find_gemini_command() -> str | None:
+    """Find the Gemini CLI command."""
+    # First try shutil.which() in case it's a real executable in PATH
+    gemini_in_path = shutil.which("gemini")
+    if gemini_in_path:
+        try:
+            # If 'gemini --version' fails, it's not the correct path
+            subprocess.run(
+                [gemini_in_path, "--version"],
+                check=True,
+                capture_output=True,
+            )
+            return gemini_in_path
+        except (subprocess.CalledProcessError, FileNotFoundError):
+            pass
+
+    # Check common installation locations (aliases don't work with subprocess)
+    potential_paths = [
+        # Default Gemini CLI installation location (after migration)
+        Path.home() / ".gemini" / "local" / "gemini",
+        # npm global installation on macOS/Linux (default)
+        Path("/usr/local/bin/gemini"),
+        # npm global installation with custom prefix
+        Path.home() / ".npm-global" / "bin" / "gemini",
+        # Homebrew installation on macOS
+        Path("/opt/homebrew/bin/gemini"),
+    ]
+
+    for path in potential_paths:
+        if path.exists():
+            # If 'gemini --version' fails, it's not the correct path
+            try:
+                subprocess.run(
+                    [str(path), "--version"],
+                    check=True,
+                    capture_output=True,
+                )
+                return str(path)
+            except (subprocess.CalledProcessError, FileNotFoundError):
+                continue
+
+    return None


The function executes subprocess.run([path, '--version']) for each potential path and when checking shutil.which() result. This creates multiple subprocess calls during discovery. Consider adding a timeout parameter to prevent hanging on unresponsive executables, or implement early termination if the first successful validation is sufficient.

Copilot · 2025-09-06T14:45:43Z

+        subprocess.run(cmd_parts, check=True, capture_output=True, text=True)
+        return True


The subprocess call lacks a timeout parameter, which could cause the installation to hang indefinitely if the Gemini CLI command becomes unresponsive. Consider adding a reasonable timeout (e.g., 30-60 seconds) to prevent blocking.

Suggested change

subprocess.run(cmd_parts, check=True, capture_output=True, text=True)

return True

subprocess.run(cmd_parts, check=True, capture_output=True, text=True, timeout=60)

return True

except subprocess.TimeoutExpired as e:

print(

f"[red]Gemini CLI command timed out after 60 seconds while installing '[bold]{name}[/bold]'.[/red]"

)

return False

jlowin · 2025-09-06T16:08:33Z

Oh good call @strawgate. You're right, this should be a uv run command. I'll open a separate issue to fix. Let's merge this, thanks @jackwotherspoon!!

jackwotherspoon · 2025-09-07T19:20:53Z

Thank a ton @strawgate @jlowin 👏

Couple quick follow-up questions:

Any time estimate on when the next release will go out with this change?
Would either or both of you be interested in collaborating on an announcement blog with me for our Google for Developers blog? I would draft it up and just get you to review and then I would put you down as a co-author(s). Similar to our VS Code Extension announcement blog.

Super excited about this integration! 😄

jlowin · 2025-09-07T19:24:15Z

Definitely this week, I think we just have a few open threads to make sure we're happy with (like content ordering) before pulling the trigger, but there's no outstanding blockers to my knowledge.
More than happy to. I'll ping you outside here to coordinate

jackwotherspoon added 5 commits September 1, 2025 14:47

chore: improve inclusive language

e8d83fb

Merge branch 'jlowin:main' into main

0749b89

chore: update gemini_cli to use latest guidance

9d3533b

chore: use success as valid integration

718d700

chore: small docs changes

60ff9e1

marvin-context-protocol Bot added enhancement Improvement to existing functionality. For issues and smaller PR improvements. cli Related to FastMCP CLI commands (run, dev, install) or CLI functionality. labels Sep 2, 2025

chore: update based on pre commit check

527e320

jackwotherspoon mentioned this pull request Sep 2, 2025

Add support for Gemini CLI integration #1708

Closed

strawgate requested changes Sep 6, 2025

View reviewed changes

Comment thread docs/integrations/gemini-cli.mdx Outdated

Small doc cleanup

f57b679

strawgate approved these changes Sep 6, 2025

View reviewed changes

Merge branch 'main' into main

1934241

strawgate requested a review from Copilot September 6, 2025 14:45

Copilot AI reviewed Sep 6, 2025

View reviewed changes

Merge branch 'main' into main

20c7e4a

jlowin merged commit e5e4262 into PrefectHQ:main Sep 6, 2025
4 checks passed

This was referenced Sep 6, 2025

Install commands assume fastmcp is globally available #1768

Closed

Clean up uvenvironment and ensure uv run --with fastmcp is used by install commands #1769

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feat: add support for Gemini CLI integration#1709

feat: add support for Gemini CLI integration#1709
jlowin merged 9 commits into
PrefectHQ:mainfrom
jackwotherspoon:main

jackwotherspoon commented Sep 2, 2025

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strawgate commented Sep 2, 2025

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jackwotherspoon commented Sep 5, 2025

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		subprocess.run(cmd_parts, check=True, capture_output=True, text=True)
		return True

-        subprocess.run(cmd_parts, check=True, capture_output=True, text=True)
-        return True
+        subprocess.run(cmd_parts, check=True, capture_output=True, text=True, timeout=60)
+        return True
+    except subprocess.TimeoutExpired as e:
+        print(
+            f"[red]Gemini CLI command timed out after 60 seconds while installing '[bold]{name}[/bold]'.[/red]"
+        )
+        return False

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jackwotherspoon commented Sep 2, 2025

Gemini CLI 🤝 FastMCP

Description

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strawgate commented Sep 2, 2025

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jackwotherspoon commented Sep 5, 2025

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Pull Request Overview

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jlowin commented Sep 6, 2025

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