skills.rest
letta-ai
letta-aiOFFICIAL
Explore all skills by this author →
Website𝕏@letta_aiGitHub

using-mcp-tools

Discover, inspect, and invoke MCP server tools through the letta mcp CLI.

3.2k|385|Updated Oct 25, 2025
Search Tags:#CLI#mcp#tool discovery#tool invocation#Letta#agent tools#schema inspection
One-click install
npx skills add https://github.com/letta-ai/letta-code --skill using-mcp-tools
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: using-mcp-tools
Source: https://github.com/letta-ai/letta-code/tree/main/src/skills/builtin/using-mcp-tools
Command: npx skills add https://github.com/letta-ai/letta-code --skill using-mcp-tools

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Agents connected to multiple MCP servers need a unified way to find the right tool, understand its schema, and call it correctly without guessing at arguments or server configurations.

Core Features & Use Cases

  • Tool Discovery and Search: List connected MCP servers, browse their tools, and run ranked hybrid, vector, or full-text search across tool schemas.
  • Schema Inspection and Invocation: Retrieve a tool's complete input schema, then call it with inline JSON arguments or file-based payloads for large inputs.
  • Troubleshooting Guidance: Diagnose missing servers, unsynced tools, stale credentials, ambiguous server names, and duplicate tool names with concrete remediation steps.
  • Use Case: An agent needs to create a calendar event but doesn't know which tool to use. It runs a search for "calendar event", inspects the top-ranked tool's schema, and calls it with the correct JSON arguments.

Quick Start

Ask the agent to search its connected MCP servers for a tool matching your task and then invoke that tool with the appropriate arguments.

Frequently Asked Questions about using-mcp-tools

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I find and call MCP tools from the command line?▼

Use letta mcp search with a query to get ranked tool schemas, then letta mcp schema to inspect one tool, and letta mcp call with --args or --args-file to invoke it. All output is JSON, including a CallToolResult with content blocks and an isError flag.

What search modes does letta mcp support?▼

The search command supports hybrid, vector, and fts modes, with hybrid as the default. Vector mode uses server-side embeddings and only covers cloud-connected servers, while fts and hybrid also rank local tools lexically.

Why does letta mcp list show no servers?▼

An empty list means no MCP servers are available to the agent. Connect a server on the Letta Cloud MCP servers page or configure a local server in the Letta Code app, then the CLI will surface it.

Why does an MCP server show zero tools?▼

A cloud server with zero tools was never synced after being connected. Resync it from the Letta Cloud MCP servers page, since the CLI itself has no refresh action.

How do I pass large JSON arguments to an MCP tool?▼

Use --args-file with a path to a JSON file, or --args-file - to read from stdin. This avoids shell-quoting problems that occur with large or complex inline JSON passed via --args.

What do letta mcp call exit codes mean?▼

Exit code 0 means success, 1 indicates a CLI or usage error with a JSON error object on stderr, and 2 means the tool ran but returned an error result. For exit code 2, read the content field for the server's message, fix the arguments, and retry.

Related Skills

Explore More Software Engineering Skills→
letta-ailetta-ai
327

lettabot

Deploys a LettaBot agent with persistent memory across multiple channels via YAML/ENV configuration.

Official
Advanced
shogo-labsshogo-labs
12

standup-collect

Collect daily standup updates and compile summaries from chat channels.

Official
Intermediate
iterateiterate
198

debug-mcp-server

Debug MCP server connections using the official MCP Inspector.

Official
Intermediate
granietgraniet
247

mcporter

Manage MCP servers and invoke tools from a unified CLI.

Community
Intermediate