perforce/p4mcp-server

Features

• Comprehensive P4 integration: Read/write tools across files, changelists, shelves, workspaces, jobs, reviews, streams, and server information.
• Code review workflows: P4 Code Review support for review discovery, voting, state transitions, commenting, and participant management.
• Safety first: Read-only mode by default, ownership checks, interactive MCP elicitation (PROCEED/CANCEL) for destructive delete and obliterate operations.
• Flexible toolsets: Configure which tool categories to enable: server, files, changelists, shelves, workspaces, jobs, reviews, and streams.
• Robust logging: Application and session logging to the logs/ directory.
• Optional telemetry: Consent-gated usage statistics. Disabled by default.
• Cross platform: Supported on macOS, Linux and Windows with pre-built binaries.

Prerequisites

• P4 Server access: Connection to a P4 Server with proper credentials
• Authentication: Valid P4 login (ticket-based or password)

System Requirements

Local P4 MCP Server Installation

Deployment

STDIO-based deployment

Configure MCP Client

Add the following to your mcp.json:

{
    "servers": {
        "perforce-p4mcp-docker": {
            "command": "docker",
            "args": [
                "run", "-i", "--rm",
                "--hostname", "your-hostname",
                "-e", "P4PORT=ssl:perforce.example.com:1666",
                "-e", "P4USER=your_username",
                "-e", "P4CLIENT=your_workspace",
                "-v", "/Users/your_username/.p4tickets:/home/mcpuser/.p4tickets:ro",
                "ghcr.io/perforce/p4mcp-server:latest"
            ]
        }
    }
}

Configuration Options

Authentication

Using P4 tickets:

# macOS/Linux
-v /Users/your_username/.p4tickets:/home/mcpuser/.p4tickets:ro

Note: Use the full path to your tickets file (not ~). After running p4 login, restart the MCP server to pick up the new ticket.

Using a password:

-e P4PASSWD="your_password"

Workspace Host Restrictions

⚠️ Important: Docker containers have their own hostname, which differs from your local machine. If your P4 workspace is restricted to a specific host, operations like sync will fail.

To resolve this, set the container hostname to match your workspace’s host restriction:

--hostname your-hostname

To find your workspace host name:

# macOS/Linux
p4 client -o your_workspace | grep "^Host:"

Mounting Client Root for Write Operations

⚠️ Important: By default, the Docker container cannot access your local workspace files. For write operations like sync, submit, or reconcile, you must mount your client root directory into the container at the same path.

Add a volume mount for your client root:

-v /path/to/your/client/root:/path/to/your/client/root

Example configuration with client root mounted:

{
    "servers": {
        "perforce-p4mcp-docker": {
            "command": "docker",
            "args": [
                "run", "-i", "--rm",
                "--hostname", "your-hostname",
                "-e", "P4PORT=ssl:perforce.example.com:1666",
                "-e", "P4USER=your_username",
                "-e", "P4CLIENT=your_workspace",
                "-v", "/Users/your_username/.p4tickets:/home/mcpuser/.p4tickets",
                "-v", "/path/to/client/root:/path/to/client/root",
                "ghcr.io/perforce/p4mcp-server:latest"
            ]
        }
    }
}

To find your client root:

p4 client -o your_workspace | grep "^Root:"

Note: The mount path inside the container must match the client root path exactly, as P4 tracks files by their absolute paths.

HTTP-based deployment

MCP client configuration

Note: In all configuration examples below, if P4CONFIG is set, you do not need to set any environment variables in the env block. The server will use the configuration from the specified P4CONFIG file instead.

Tip: If you have uv installed, you can use uvx p4mcp-server instead of /absolute/path/to/p4-mcp-server in the command field. This eliminates the need to download or build binaries manually.

P4 Environment Variables

• P4PORT - P4 Server address. Examples: ssl:perforce.example.com:1666, localhost:1666
• P4USER - Your P4 username
• P4CLIENT - Your current P4 workspace. Optional, but recommended

Result limit environment variables

• P4MCP_MAX_RESULTS - Cap on the number of rows the P4 server returns per command (p4.maxresults). Default: 10000. Set to 0 to disable the limit (server default in effect). When a command would exceed this limit the server aborts it with an error rather than truncating results, so keep the value generous. Can be overridden by the --max-results CLI argument. Must be a non-negative integer; an invalid value fails fast at startup before any P4 connection is attempted.
• P4MCP_MAX_SCAN_ROWS - Cap on the number of rows the P4 server scans per command (p4.maxscanrows). Unset by default, so admin/group policy governs scan limits. Can be overridden by the --max-scan-rows CLI argument. Must be a non-negative integer when supplied.

Logging environment variables

• P4MCP_LOG_DIR - Directory for log files. Default: logs/ in the server executable’s directory. Can be overridden by the --log-dir CLI argument.

SSL/TLS environment variables

• P4MCP_TLS_CA_MODE - TLS certificate source mode.
  • system (default): use OS trust store via truststore. Note: In this mode, truststore overrides the verify= parameter — custom CA bundles set via P4MCP_CA_BUNDLE or --ca-bundle are ignored. To use a custom CA bundle, set P4MCP_TLS_CA_MODE=certifi.
  • certifi: disable truststore injection and use default Python TLS certificate behavior. Custom CA bundles (P4MCP_CA_BUNDLE / --ca-bundle) take effect only in this mode.
• P4MCP_SSL_VERIFY - Set to false to disable SSL verification for P4 Code Review API requests. Default: true. Works in both TLS modes.
• P4MCP_CA_BUNDLE - Path to a custom CA certificate bundle (PEM) for P4 Code Review API requests. Takes priority over P4MCP_SSL_VERIFY. Requires P4MCP_TLS_CA_MODE=certifi to take effect.

Telemetry environment variables

• OTEL_EXPORTER_OTLP_ENDPOINT - OTLP collector endpoint for telemetry export. Default: https://grpc.public.prd.shared.perforce.com.
• OTEL_EXPORTER_OTLP_PROTOCOL - OTLP export protocol. Only grpc is supported; other values fall back to grpc with a warning.

Supported arguments

• --readonly - Control write operations.

  • If present, uses read-only mode. Safe for exploration and testing.
  • If missing, enables write operations. Requires proper permissions on your P4 Server.

• --allow-usage - Allow usage statistics.

  • If present, allows anonymous usage statistics collection.
  • If missing, disables all usage statistics.

• --toolsets - Specify which tool categories to enable.

  • Available: files, changelists, shelves, workspaces, jobs, reviews, streams
  • Default: All toolsets enabled.
  • query_server is always available regardless of the --toolsets setting.

• --search-transform - Enable search-based tool discovery to reduce token overhead.

  • regex — Expose a regex pattern-matching search tool. Best for targeted lookups.
  • bm25 — Expose a natural-language relevance-ranked search tool. Best for exploratory queries.
  • both — Expose both search tools with distinct names (regex_search_tools/regex_call_tool and semantic_search_tools/semantic_call_tool).
  • If omitted, the full tool catalog is sent to the client (default, backward-compatible).
  • When enabled, query_server is always directly visible to the client.
  • Security: Admin permission checks (CheckPermissionMiddleware) and --readonly filtering remain fully enforced. Search transforms query the real tool catalog internally, so tools blocked by middleware or excluded by read-only mode are never discoverable or callable through the search interface.

• --max-results - Cap on the number of rows the P4 server returns per command (p4.maxresults).

  • Default: 10000. Set to 0 to disable the limit (server default in effect).
  • Protects against runaway AI-driven queries exhausting local memory or overwhelming the server.
  • When a command would exceed this limit the server aborts it with an error — it does not truncate — so keep the value generous.
  • Must be a non-negative integer; an invalid value fails fast at startup before any P4 connection is attempted.

  Priority order: --max-results > P4MCP_MAX_RESULTS > default (10000).

• --max-scan-rows - Cap on the number of rows the P4 server scans per command (p4.maxscanrows).

  • Unset by default, so admin/group policy governs scan limits.
  • Must be a non-negative integer when supplied; an invalid value fails fast at startup.

  Priority order: --max-scan-rows > P4MCP_MAX_SCAN_ROWS > default (unset).

• --ssl-no-verify - Disable SSL certificate verification for P4 Code Review API requests.

  • Useful for environments with self-signed or internal CA certificates.
  • Works in both system and certifi TLS modes.
  • These SSL options only affect HTTPS Swarm connections. If the Swarm URL is http://, they have no effect.

• --ca-bundle - Path to a custom CA certificate bundle (PEM) for P4 Code Review API requests.

  • Use this to trust an internal CA without disabling verification entirely.
  • Requires P4MCP_TLS_CA_MODE=certifi to take effect. In the default system mode, truststore uses the OS trust store and ignores this setting.
  • If both --ca-bundle and --ssl-no-verify are provided, --ca-bundle takes priority (verification is performed using the specified bundle).

  Priority order: --ca-bundle > --ssl-no-verify > P4MCP_CA_BUNDLE > P4MCP_SSL_VERIFY > default (true). CLI args take priority over environment variables.

• --log-dir - Directory for log files.

  • Specify a custom directory for log files (both application and session logs).
  • Default: logs/ in the server executable’s directory.
  • Can also be set via P4MCP_LOG_DIR environment variable.
  • CLI argument takes priority over environment variable.

  Priority order: --log-dir > P4MCP_LOG_DIR > default (logs/ in the server executable’s directory).

Required configurations

• Use absolute paths for the command field in all configurations.
• Ensure environment variables are properly set for each host.
• Different hosts may have different argument parsing. Refer to the host’s documentation.

P4 configuration

User configuration

Example setup

# Windows (PowerShell)
$env:P4PORT = "ssl:perforce.example.com:1666"
$env:P4USER = "your_username"
$env:P4CLIENT = "your_workspace"

# macOS/Linux (Bash)
export P4PORT="ssl:perforce.example.com:1666"
export P4USER="your_username"
export P4CLIENT="your_workspace"

P4USER must be a standard user. P4 MCP Server runs commands such as p4 describe and p4 changes that a service-type user is not permitted to run, so a service user will cause tools to fail at runtime. Configure P4USER with a Perforce user of type standard. See p4 user in the P4 CLI documentation.

Connection-limit options

These options bound how much work a single P4 command can do, protecting the server against runaway queries:

• max_results — Caps how many rows the P4 server returns per command. On by default with a generous value to protect against runaway queries. Lower the value to tighten the bound. Configured via P4MCP_MAX_RESULTS or --max-results.
• max_scan_rows — Caps how many rows the server scans per command. Unset by default (governed by admin/group policy). Configured via P4MCP_MAX_SCAN_ROWS or --max-scan-rows.

Admin configuration

Manage access through group-level and user-level server properties. P4 resolves each property to a single value using two rules, applied in order:

1. Highest sequence number wins. The -s flag is the primary sort key. It applies across all scopes — a group property at -s5 beats a user property at -s1 or default.
2. At the same sequence number, scope is the tiebreaker: user > group > global. Between groups at the same sequence, the alphabetically-first group name wins.

P4 does not compare values semantically. It does not know that false is more restrictive than true. The winning property’s value is returned as-is and checked by the MCP server.

If no property applies, MCP remains enabled unless explicitly disabled.

Master switch (global disable)

To disable MCP for all users:

p4 property -a -n mcp.enabled -v false

To re-enable group/user-based control, delete the global property first:

p4 property -d -n mcp.enabled

How properties are resolved

The MCP server checks properties in this order. Each property is resolved independently by P4 using the standard resolution rules (highest -s wins, then user > group > global at equal sequence, then alphabetically-first group name).

Important notes

• Each property is resolved to a single value by P4 before the MCP server sees it. P4 uses: highest sequence number (-s) first, then scope (user > group > global) as a tiebreaker, then alphabetical group name. The MCP server does not perform its own multi-group or multi-scope resolution.

• mcp.enabled acts as the main switch. When its resolved value is false, all access is blocked.

• At the same sequence number, a group or user property overrides a global property. To ensure a global false cannot be overridden, assign it a high -s value.

• Scope hierarchy (user > group > global) only applies as a tiebreaker at equal sequence numbers. A group property at -s5 will beat a user property at default sequence or -s1.

• When a user belongs to multiple groups, the alphabetically-first group name wins (at equal -s). The winning value is used as-is — P4 does not compare true vs false or pick the “most restrictive” value. Use explicit -s values to control which group takes priority.

• Tool-specific overrides (mcp.toolset..tools) can further restrict access but cannot bypass write restrictions. Write checks are evaluated before tool lists.

• Property changes take effect within 60 seconds due to server-side caching, or immediately on a new MCP server connection.

• Only the value false (case-insensitive) disables or blocks access. Any other value (including true, 1, yes, or invalid strings) is treated as not blocking.

Available tools

Query tools (read operations)

Modify tools (write operations)

Warnings in tool responses

When a P4 command produces a benign informational or warning message (for example, file(s) up-to-date or file not on client), the tool returns a success status and includes the message text in an optional top-level warnings list. The field appears only when there is at least one warning. Genuine failures are unaffected and still return an error status with the existing code and error fields.

Logging and Usage Data

Logging system

Log locations:

• Application log: logs/p4mcp.log - Main server operations and errors
• Session logs: logs/sessions/*.log - Individual session activities are recorded only when the --allow-usage flag is specified in the server’s startup arguments.

Usage Data

Privacy-first approach:

• Disabled by default: No data collection without explicit consent
• Consent-gated: First-run prompt for telemetry permission
• Transparent: Clear explanation of data collected
• Revocable: Easy opt-out at any time

Data collected (if consented):

• Tool usage frequency (anonymized)
• Error rates and types (no personal data)
• Performance metrics
• Feature adoption statistics
• P4 server version

Data not collected:

• File contents or names
• P4 Server details except version
• User credentials or personal information
• Specific project information

Control:

• Usage data is only collected if the --allow-usage argument is provided at startup.

Troubleshooting

Server Startup Issues

Connection Issues

Authentication Problems

Workspace Issues

Permission Errors

Performance Issues

Tool Execution

Common Error Patterns

1. Authentication: Ensure valid login before MCP operations.
2. Workspace mapping: Verify client views include target files.
3. Permissions: Check user and file permissions for write operations.
4. Network: Verify connectivity for remote P4 Servers.

Getting Help

1. Check the logs: Always check logs/p4mcp.log first.
2. Test P4: Ensure p4 info works before troubleshooting MCP.
3. Report issues to the community: Report issues with log excerpts and environment details.

Support

Perforce P4 MCP Server is a community supported project and is not officially supported by Perforce. Pull requests and issues are the responsibility of the project’s moderator(s); this may be a vetted individual or team with members outside of the Perforce organization. All issues should be reported and managed via GitHub (not via Perforce’s standard support process).

Contributions

We welcome contributions to the P4 MCP Server project.

License

This project is licensed under the MIT License. See LICENSE for details.

Third-Party Notices

This project includes third-party components. Their licenses and attributions are listed in THIRD-PARTY-NOTICES.