LangSmith MCP Server
Server Configuration
Describes the environment variables required to run the server.
| Name | Required | Description | Default |
|---|---|---|---|
| LANGSMITH_API_KEY | Yes | Your LangSmith API key | |
| LANGSMITH_ENDPOINT | No | Optional endpoint for on-prem deployments |
Instructions
Guidance the server publishes about itself, which clients place ahead of the tool catalog so the model reads it before choosing anything.
This server publishes no instructions, or was last inspected before Glama recorded them.
Capabilities
Features and capabilities supported by this server
Protocol revision2025-11-25
| Capability | Details |
|---|---|
| tools | {
"listChanged": true
} |
| prompts | {
"listChanged": false
} |
| resources | {
"subscribe": false,
"listChanged": false
} |
| experimental | {} |
Tools
Functions exposed to the LLM to take actions
| Name | Description |
|---|---|
| ls_list_runsA | List recent runs from LangSmith (root-only by default). Args: project_name: LangSmith project name (required) is_root: Only return root runs when true (default: True) run_type: Filter by run type (e.g., 'llm', 'chain', 'tool') error: Filter by error status - True=failed only, False=successful only, None=all start_minutes_ago: Lookback window in minutes (default: 1440 = 24 hours, min: 1) limit: Maximum runs to return (default: 50, range: 1-200) select: List of fields to return (default: id, name, run_type, start_time, end_time, error, tags, extra) |
| ls_read_runA | Read a single run with optional children hydration. Args: run_id: Run ID to fetch (required) hydrate_children: Include child spans in response (default: False) child_limit: Maximum children to return when hydrate_children=True (default: 100, range: 1-500) |
| ls_get_run_urlA | Generate a shareable LangSmith UI URL for a run. Args: run_id: Run ID to generate URL for (required) Returns: Shareable LangSmith URL (e.g., https://smith.langchain.com/o/.../runs/...) |
| ls_list_childrenA | List child spans for a given parent run. Args: parent_run_id: Parent run ID (required) limit: Maximum children to return (default: 100, range: 1-500) Returns: List of child run objects with id, name, run_type, timing, and error info |
| ls_list_projectsA | List projects from LangSmith workspace. Args: limit: Maximum projects to return (default: 10, range: 1-200) Returns: List of project objects with id, name, start_time, tenant_id, and optional statistics |
Prompts
Interactive templates invoked by user choice
| Name | Description |
|---|---|
No prompts | |
Resources
Contextual data attached and managed by the client
| Name | Description |
|---|---|
No resources | |
TDQS
Scored across 5 tools
Each tool targets a distinct resource and action: listing runs, reading a single run, generating a URL, listing children, and listing projects. There is no ambiguity or overlap between them.
All tools share a consistent 'ls_' prefix, but the verbs mix 'list', 'read', and 'get', creating a slight inconsistency. The pattern is still readable and predictable, but not as uniform as a pure verb_noun convention.
Five tools is a well-scoped set for exploring LangSmith runs and projects. Each tool serves a specific purpose without redundancy or bloat.
The set covers all essential read-only workflows for runs, children, and projects. Minor gaps exist, such as no direct project detail tool or search/filter beyond what's offered, but these are workarounds and not dead ends.