instruments-mcp-server: Instructions file for Claude Code

CLAUDE.md

instruments-mcp-server CLAUDE.md is an instructions file for Claude Code from nemanjavlahovic/instruments-mcp-server. It costs 480 tokens per session, scanned A, original, MIT.

An MCP server for Apple’s Xcode Instruments, a performance-analysis tool for iPhone, iPad, and Mac applications. It collects trace data and turns it into structured results with severity labels and summaries.

In plain words
What is it for?
Use it to profile apps, inspect raw traces, analyze performance data, compare results with a baseline, and examine memory, launch time, networking, energy, or SwiftUI behavior.
Why use it?
It reduces the manual work of reading performance traces and makes problems such as slow code, memory leaks, hangs, or high energy use easier to identify.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md.

This is nemanjavlahovic/instruments-mcp-server's own configuration. It tells Claude Code how to work on instruments-mcp-server itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything instruments-mcp-server configures →

Reuse

Borrowing it

Nothing to install: this file belongs to nemanjavlahovic/instruments-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/nemanjavlahovic/instruments-mcp-server/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/nemanjavlahovic/instruments-mcp-server

Made for: Claude Code.

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Per session 480 This file is loaded in full into every session.
When invoked 480 The same file — it is already loaded in full.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00480 $0.00480
Opus 5 $0.00240 $0.00240
Sonnet 5 $0.00096 $0.00096
Haiku 4.5 $0.00048 $0.00048

Measured 7d ago against content hash 326b21165e76, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

instruments-mcp-server CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 7d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 37 lines

What it actually says

InstrumentsMCP

What This Is

AI-native performance profiling for iOS and macOS apps. Wraps Xcode Instruments (xctrace CLI) as an MCP server, parsing trace data into structured JSON with severity classifications and actionable summaries.

Architecture

  • src/index.ts - MCP server entry point, registers all tools
  • src/tools/ - Tool definitions (profile, list, analyze, baseline)
  • src/parsers/ - Template-specific XML→JSON parsers (time-profiler, swiftui, allocations, hangs, app-launch, energy, leaks, network)
  • src/utils/xctrace.ts - Low-level xctrace CLI wrapper
  • src/utils/xml.ts - XML parsing with fast-xml-parser

Key Design Decisions

  • Each Instruments template has its own parser with domain-specific heuristics
  • Severity classification (ok/warning/critical) uses tuned thresholds per metric type
  • The profile_raw + analyze_trace combo handles any template without a dedicated parser
  • Traces are stored in ~/.instruments-mcp/traces/ with timestamps

Adding New Parsers

  1. Create src/parsers/<template-name>.ts
  2. Export a parse function that takes TOC XML + table XML and returns structured data
  3. Add a dedicated profile_<name> tool in src/tools/profile.ts
  4. Include severity classification and a text summary

xctrace Compatibility

  • xctrace 26+ uses Deferred recording mode by default — time-profile table may be empty
  • profile_cpu and performance_audit fall back to time-sample table automatically
  • xctraceExport retries up to 5 times for intermittent "Document Missing Template Error"
  • XML parser isArray config wraps node, row, frame, backtrace etc. in arrays — always unwrap [0]
  • xctrace 26 backtrace frames use @_name for function names and nested binary.@_name for module

Tech Stack

  • TypeScript, Node.js >= 20, ESM modules
  • @modelcontextprotocol/sdk for MCP protocol
  • fast-xml-parser for XML→JS conversion
  • zod for tool parameter schemas
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 7d ago First seen · 37 lines · 480 tokens per session scan A 326b21165e76

Subscribe to this mod's changes

instruments-mcp-server CLAUDE.md is an instructions file published in the GitHub repository nemanjavlahovic/instruments-mcp-server (19 stars, last pushed 4mo ago), licensed MIT. It adds 480 tokens to every session, about $0.0024 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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