User Request	Tool
Trace, execution flow, show function calls	xtrace
Step debugging, breakpoints, inspect variables, track variable changes	xstep
Profile, performance, bottlenecks, slow code	xprofile
Coverage, test coverage, which lines tested	xcoverage
Backtrace, call stack, how did we get here	xback

"Trace" Ambiguity

The word "trace" can mean different things:

Forward Trace → xtrace (records execution from start to finish)
Backtrace / Stack Trace → xback (shows call stack at a point)
Step through / Debug → xstep (interactive with breakpoints)

xtrace - Forward Trace (Full)

Trace execution forward from start to finish. Captures complete execution flow, function calls, parameters, and timing data.

Output: JSON with $schema URL for semantic details and AI analysis strategies. Key fields: {lines, functions, max_depth, db_queries}

~/.composer/vendor/bin/xtrace [--json] [--context=TEXT] [--include-vendor=PATTERNS] -- command

Examples

~/.composer/vendor/bin/xtrace --context="Debug login" -- php login.php
~/.composer/vendor/bin/xtrace --context="Test analysis" -- vendor/bin/phpunit tests/UserTest.php
~/.composer/vendor/bin/xtrace --include-vendor="bear/*" -- php app.php

When to Use

"Trace this code"
"Show execution flow"
"What functions are called?"
General PHP debugging (default choice)

xstep - Forward Trace (Step-by-Step)

Stop at breakpoint, step forward N times, record variable changes at each step. See how variable values affect branching ("this variable was X, so it went into this branch").

Output: JSON with $schema URL for semantic details. Key fields: {breaks: [{step, location, variables}]} - Variables show diff only (changed values).

~/.composer/vendor/bin/xstep --break=file.php:line --steps=N [--context=TEXT] [--include-vendor=PATTERNS] -- command

Options

--break=file.php:line - Single breakpoint location
--break=file.php:line:condition - Conditional (e.g., $user==null)
--steps=N - Step forward N times from breakpoint
--watch=EXPR - Only record steps when expression value changes (can specify multiple times)

Examples

# Step 20 times from line 42
~/.composer/vendor/bin/xstep --break="user.php:42" --steps=20 --context="Track auth" -- php user.php

# Conditional breakpoint
~/.composer/vendor/bin/xstep --break="user.php:15:\$id==null" --steps=10 -- php user.php

# Watch variable changes in loop
~/.composer/vendor/bin/xstep --break="loop.php:10" --watch="\$i" --steps=100 -- php loop.php

# Multiple watches
~/.composer/vendor/bin/xstep --break="app.php:25" --watch="\$user->getStatus()" --watch="count(\$items)" --steps=50 -- php app.php

Workflow Tips

Need more steps? Set new breakpoint at where you stopped, run again
Too much variable info? Use xtrace first to see flow, then xstep for details

When to Use

"Track how variable changes step by step"
"Why did it branch this way?"
"What's the variable value at line X?"

xprofile - Performance Profiler

Identify performance bottlenecks with precision data.

Output: JSON with $schema URL for semantic details and AI analysis strategies. Key fields: {time_ms, memory_mb, bottlenecks} - Bottlenecks auto-identified.

~/.composer/vendor/bin/xprofile [--json] [--context=TEXT] [--include-vendor=PATTERNS] -- command

Examples

~/.composer/vendor/bin/xprofile --context="Optimize processing" -- php process.php
~/.composer/vendor/bin/xprofile --json -- php script.php
~/.composer/vendor/bin/xprofile --include-vendor="doctrine/*" -- php app.php

When to Use

"Profile this code"
"Find bottlenecks"
"Why is this slow?"
"Memory usage analysis"

xcoverage - Code Coverage

Collect code coverage data for PHPUnit or any PHP script. Shows only uncovered lines (compact output).

Output: JSON with $schema URL for semantic details. Key fields: {summary: {coverage_percent, covered_lines, uncovered_lines}, uncovered: {file: [lines]}}

~/.composer/vendor/bin/xcoverage [--include-vendor=PATTERNS] -- command
~/.composer/vendor/bin/xcoverage -- vendor/bin/phpunit        # PHPUnit
~/.composer/vendor/bin/xcoverage -- php script.php            # Any PHP script

Examples

~/.composer/vendor/bin/xcoverage -- vendor/bin/phpunit
~/.composer/vendor/bin/xcoverage --include-vendor="bear/*,ray/di" -- vendor/bin/phpunit
~/.composer/vendor/bin/xcoverage -- vendor/bin/phpunit --filter testMethod

When to Use

"Check test coverage"
"Which lines are tested?"
"Find untested code"

xback - Backtrace Capture

Get call stack (backtrace) at a specific line. Shows "who called this?" - the chain of function calls that led to this point.

Output: JSON with $schema URL for semantic details. Key fields: {backtrace: [{file, line, function, args}]}

~/.composer/vendor/bin/xback [--break=SPEC] [--depth=N] [--context=TEXT] -- command

Examples

~/.composer/vendor/bin/xback -- php script.php                    # First line
~/.composer/vendor/bin/xback --break=app.php:50 -- php app.php    # At breakpoint
~/.composer/vendor/bin/xback --depth=20 -- php main.php           # Deep trace

When to Use

"Get backtrace at line X"
"Show call stack"
"How did execution reach this line?"

Common Options

Option	Description
`--json`	AI-optimized JSON output
`--context=TEXT`	Add description for AI analysis
`--include-vendor=PATTERNS`	Include vendor packages

Vendor Filtering

By default, vendor code is excluded to focus on your code. Use --include-vendor when needed:

--include-vendor="bear/*"           # Include specific framework
--include-vendor="bear/*,ray/di"    # Multiple packages
--include-vendor="*/*"              # Include all vendor (framework debugging)

JSON Schemas

xtrace: https://koriym.github.io/xdebug-mcp/schemas/xtrace.json
xstep: https://koriym.github.io/xdebug-mcp/schemas/xstep.json
xprofile: https://koriym.github.io/xdebug-mcp/schemas/xprofile.json
xcoverage: https://koriym.github.io/xdebug-mcp/schemas/xcoverage.json
xback: https://koriym.github.io/xdebug-mcp/schemas/xback.json

Tool	Path
xtrace	`~/.composer/vendor/bin/xtrace`
xstep	`~/.composer/vendor/bin/xstep`
xprofile	`~/.composer/vendor/bin/xprofile`
xcoverage	`~/.composer/vendor/bin/xcoverage`
xback	`~/.composer/vendor/bin/xback`

xdebug

Xdebug MCP Tools

Tool Paths

Tool Selection Guide