langsmith-fetch-skill MCP — Use Cases, Install & Live Demo

Why use it

Key features

Pulls traces directly from LangSmith Studio via CLI
Auto-triggers on debugging-flavored prompts
Tracks failures + root causes
Latency + token usage analysis
Tool-call and memory operation review
Session export

Live Demo

What it looks like in practice

langsmith-fetch-skill.replay ▶ ready

0/0

Install

Pick your client

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "langsmith-fetch-skill": {
      "command": "git",
      "args": [
        "clone",
        "https://github.com/OthmanAdi/langsmith-fetch-skill",
        "~/.claude/skills/langsmith-fetch-skill"
      ],
      "_inferred": true
    }
  }
}

Open Claude Desktop → Settings → Developer → Edit Config. Restart after saving.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "langsmith-fetch-skill": {
      "command": "git",
      "args": [
        "clone",
        "https://github.com/OthmanAdi/langsmith-fetch-skill",
        "~/.claude/skills/langsmith-fetch-skill"
      ],
      "_inferred": true
    }
  }
}

Cursor uses the same mcpServers schema as Claude Desktop. Project config wins over global.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "langsmith-fetch-skill": {
      "command": "git",
      "args": [
        "clone",
        "https://github.com/OthmanAdi/langsmith-fetch-skill",
        "~/.claude/skills/langsmith-fetch-skill"
      ],
      "_inferred": true
    }
  }
}

Click the MCP Servers icon in the Cline sidebar, then "Edit Configuration".

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "langsmith-fetch-skill": {
      "command": "git",
      "args": [
        "clone",
        "https://github.com/OthmanAdi/langsmith-fetch-skill",
        "~/.claude/skills/langsmith-fetch-skill"
      ],
      "_inferred": true
    }
  }
}

Same shape as Claude Desktop. Restart Windsurf to pick up changes.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "langsmith-fetch-skill",
      "command": "git",
      "args": [
        "clone",
        "https://github.com/OthmanAdi/langsmith-fetch-skill",
        "~/.claude/skills/langsmith-fetch-skill"
      ]
    }
  ]
}

Continue uses an array of server objects rather than a map.

~/.config/zed/settings.json

{
  "context_servers": {
    "langsmith-fetch-skill": {
      "command": {
        "path": "git",
        "args": [
          "clone",
          "https://github.com/OthmanAdi/langsmith-fetch-skill",
          "~/.claude/skills/langsmith-fetch-skill"
        ]
      }
    }
  }
}

Add to context_servers. Zed hot-reloads on save.

claude mcp add langsmith-fetch-skill -- git clone https://github.com/OthmanAdi/langsmith-fetch-skill ~/.claude/skills/langsmith-fetch-skill

One-liner. Verify with claude mcp list. Remove with claude mcp remove.

Use Cases

Real-world ways to use langsmith-fetch-skill

Diagnose a slow agent without opening LangSmith UI

👤 LangChain/LangGraph devs ⏱ ~20 min intermediate

When to use: An agent that used to be snappy is now slow; you want root cause.

Prerequisites

LangSmith API key — smith.langchain.com -> Settings -> API Keys
Skill installed — git clone https://github.com/OthmanAdi/langsmith-fetch-skill ~/.claude/skills/langsmith-fetch-skill

Flow

Ask Claude to diagnose

Why is my agent <name> slow? Pull the last 20 traces from LangSmith and find the hotspot.✓ Copied

→ Skill fetches traces; reports latency by step
Drill in

Focus on trace <id> — break down tool-call times.✓ Copied

→ Per-tool latency with the outlier called out

Outcome: A specific step to optimize, not a hunch.

Pitfalls

Optimizing the average when tail latency is the problem — Ask for p95/p99 specifically

Combine with: filesystem

Root-cause an agent failure from a trace id

👤 Anyone running LangGraph in production ⏱ ~15 min intermediate

When to use: A user reported an error; you have the trace id.

Flow

Fetch + analyze

Debug trace <id>. What was the immediate error, what's the root cause in the graph?✓ Copied

→ Error step + upstream decision that led to it

Outcome: A fix targeting the actual decision point, not the symptom.

Find which node burns the most tokens

👤 Teams optimizing LLM spend ⏱ ~30 min intermediate

When to use: Monthly review of agent spend.

Flow

Aggregate token usage

Across last 7 days' traces, rank graph nodes by total token usage.✓ Copied

→ Ranked table with % share
Propose tightening

For the top 3, propose prompt-compression or model downgrade options.✓ Copied

→ Targeted opt list

Outcome: Measurable spend reduction without chasing tiny savings.

Combinations

Pair with other MCPs for X10 leverage

langsmith-fetch-skill + filesystem

Save exports alongside the agent code for lineage

Export the debugging session to debugging/traces/<date>.json.✓ Copied

langsmith-fetch-skill + github

Attach trace summary to a bug report

Summarize trace <id> and post as comment on GitHub issue #42.✓ Copied

Tools

What this MCP exposes

Tool	Inputs	When to call	Cost
fetch_recent	project, limit	Broad diagnosis	LangSmith quota
fetch_trace	trace_id	Deep dive on one run	LangSmith quota
analyze_failures	traces	Post-fetch analysis	0
export_session	traces	Archive for later	0

Cost & Limits

What this costs to run

API quota: LangSmith: depends on plan; Studio has generous quotas
Tokens per call: Low — traces are structured
Monetary: Free skill; LangSmith free tier covers most devs
Tip: Use fetch_recent with a narrow window, not full history

Security

Permissions, secrets, blast radius

Minimum scopes: LangSmith: read on your project(s)

Credential storage: LANGCHAIN_API_KEY in env

Data egress: Only to LangSmith (where the traces already live)

Never grant: Write to LangSmith — skill only reads

Traces can include user inputs and outputs — treat them as user data under your privacy policy.

Troubleshooting

Common errors and fixes

langsmith-fetch: command not found

Install LangSmith CLI or ensure it's on PATH

Verify: which langsmith-fetch

Empty results

Check project name and time window; traces are project-scoped

Alternatives

langsmith-fetch-skill vs others

Alternative	When to use it instead	Tradeoff
LangSmith web UI	You prefer clicking	No Claude analysis

More

Resources

📖 Read the official README on GitHub

🐙 Browse open issues

🔍 Browse all 400+ MCP servers and Skills