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Agent skill

Using MCP Tools

by letta-ai in letta-ai/letta-code

Reference for the letta mcp CLI, which finds and invokes MCP tools available to this agent.

Apache-2.0Auto-check passedAgent Workflows

Install Using MCP Tools

skills CLI
$ npx skills add letta-ai/letta-code --skill using-mcp-tools -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install letta-ai/letta-code using-mcp-tools --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/letta-ai/letta-code.git skills-src && mkdir -p .claude/skills && cp -r skills-src/src/skills/builtin/using-mcp-tools .claude/skills/using-mcp-tools && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
using-mcp-tools
GitHub stars
3.6k
Token cost
~890 tokens
SKILL.md length
376 words
Files
1
Skills in repo
25
Repo updated
First seen
Licence
Apache-2.0

At a glance

Reference for the letta mcp CLI, which finds and invokes MCP tools available to this agent.

  • Tasks that involve MCP servers
  • SKILL.md covers Commands, Search options, Call arguments and results and Troubleshooting
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Using MCP Tools is an agent skill from letta-ai/letta-code. Reference for the letta mcp CLI, which finds and invokes MCP tools available to this agent. A system reminder already lists your connected MCP servers and the basic search/schema/call commands; invoke this skill when you need more — browsing a server's tools, passing large or file-based arguments, tuning search, or troubleshooting missing servers, tools, and errors.

Its SKILL.md is about 890 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Agent Workflows, covering MCP servers. It works with Model Context Protocol and Letta. The repository describes itself as: Stateful agents that are like people, with memory, identity, and the ability to learn and adapt. The licence is Apache-2.0.

When your agent uses it

  • Tasks that involve MCP servers

Example prompts

  • “/using-mcp-tools”

What it can do on your machine

Read from SKILL.md and the folder at commit d31b879. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are bash).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Using MCP Tools loads about 890 tokens when it runs. Until then it costs about 97 tokens; SKILL.md has 376 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~97
When it runs · the whole SKILL.md, loaded when a task matches
~890

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from letta-ai/letta-code at commit d31b879, republished under its Apache-2.0 licence (© letta-ai). 376 words, ~890 tokens.

Download SKILL.mdSave it as .claude/skills/using-mcp-tools/SKILL.md (or your agent's skills folder).
name
using-mcp-tools
description
Reference for the `letta mcp` CLI, which finds and invokes MCP tools available to this agent. A system reminder already lists your connected MCP servers and the basic search/schema/call commands; invoke this skill when you need more — browsing a server's tools, passing large or file-based arguments, tuning search, or troubleshooting missing servers, tools, and errors.

Using MCP tools

letta mcp gives the agent one unified view of every MCP server it can reach: servers connected to the agent in Letta Cloud and servers configured locally on this machine. It works from any surface where the agent runs — cloud sandboxes (chat.letta.com), Letta Desktop, and terminals. All output is JSON.

Commands

bash
letta mcp list                                # servers: [{name, transport}]
letta mcp get <server>                        # one server's connection configuration (credentials redacted)
letta mcp tools [server]                      # tool names + descriptions only
letta mcp tools [server] --full               # ...including every tool's complete schema
letta mcp schema <tool-name>                  # one tool's complete schema
letta mcp search <query> [--mode] [--limit]   # ranked tool schemas: [{tool, rank, score}]
letta mcp call <tool-name> [--args | --args-file]  # run a tool, print a CallToolResult

Every command accepts --agent <id>, defaulting to LETTA_AGENT_ID/AGENT_ID — do not pass it unless targeting another agent.

Search options

  • --mode <hybrid|vector|fts> — default hybrid. vector uses server-side embeddings and covers only cloud-connected servers; fts and hybrid also rank local tools lexically. Agents on a local backend cannot use vector.
  • --limit <n> — result count, 1-100 (default 5).
  • Rank order is meaningful; absolute scores are not comparable across queries. When even the top results look unrelated to the query, no relevant tool likely exists — do not force the best-ranked one.

Call arguments and results

  • --args '<json>' — inline JSON object.
  • --args-file <path> — read the JSON object from a file; --args-file - reads stdin. Use these for large or shell-quoting-hostile payloads.
  • Output is an MCP CallToolResult: content (array of typed blocks), optional structuredContent, and isError.
  • Exit codes: 0 success, 1 CLI/usage error (JSON on stderr: {error: {code, message, hint?}}), 2 the tool ran and returned an error result — read content for the server's message, fix the arguments, and retry.
  • Summarize relevant results instead of pasting large raw payloads.
Show full SKILL.md (151 more words)Show less

Troubleshooting

  • list empty → no MCP servers are available. Ask the user to connect one on the Letta Cloud MCP servers page or configure a local one in the Letta Code app.
  • Cloud server with no tools (or 0 tools in the reminder) → tools were never synced. Ask the user to resync it from the MCP servers page; the CLI has no refresh action.
  • unauthorized or another auth error on call → the server's stored credentials are missing or stale (tools can still list from previously synced rows). Ask the user to re-authenticate the server: cloud servers on the MCP servers page, local OAuth servers by connecting once in the Letta Code app — this CLI is non-interactive and only reuses persisted credentials.
  • ambiguous_server_name → two servers share a name; the error hint explains how to disambiguate.
  • Duplicate tool names across servers get a numeric suffix (_2); the printed name is always the callable one.

© letta-ai, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in src/skills/builtin/using-mcp-tools of letta-ai/letta-code.

Open the folder on GitHubat commit d31b879

Compare with similar skills

Using MCP Tools next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Using MCP Tools compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Using MCP Tools this skillletta-ai/letta-code3.6k—~890Automated safety check: PassApache-2.0
MCP Server Builderanthropics/skills180k63 repos~2.3kAutomated safety check: PassApache-2.0
MCP Server BuildershareAI-lab/learn-claude-code78k4 repos~1.2kAutomated safety check: PassMIT
MCP Integration for Pluginsanthropics/claude-plugins-official38k11 repos~3.1kAutomated safety check: PassApache-2.0
Crush Configurationcharmbracelet/crush29k—~3.7kAutomated safety check: PassCustom licence
Context Mode Output Sandboxmksglu/context-mode26k—~4.1kAutomated safety check: PassCustom licence

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Works with

Categories

Questions about Using MCP Tools

What does Using MCP Tools do?

Reference for the letta mcp CLI, which finds and invokes MCP tools available to this agent. Using MCP Tools is an agent skill from letta-ai/letta-code. Reference for the letta mcp CLI, which finds and invokes MCP tools available to this agent.

When should I use Using MCP Tools?

Using MCP Tools fits situations like: tasks that involve MCP servers.

How do I install Using MCP Tools in Claude Code?

Run `npx skills add letta-ai/letta-code --skill using-mcp-tools -a claude-code`. Or copy the skill folder (src/skills/builtin/using-mcp-tools in letta-ai/letta-code) into .claude/skills/using-mcp-tools in your project. Claude Code loads it when a task matches its description.

How do I install Using MCP Tools in Codex?

Run `npx skills add letta-ai/letta-code --skill using-mcp-tools -a codex`. Or copy the skill folder (src/skills/builtin/using-mcp-tools in letta-ai/letta-code) into .agents/skills/using-mcp-tools in your project. Codex loads it when a task matches its description.

Can I use Using MCP Tools in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add letta-ai/letta-code --skill using-mcp-tools -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/using-mcp-tools, .gemini/skills/using-mcp-tools, .github/skills/using-mcp-tools and .opencode/skills/using-mcp-tools in your project.

What does Using MCP Tools need to run?

SKILL.md names no scripts, command-line tools or credentials: Using MCP Tools is instructions for the agent only.

Does Using MCP Tools access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Using MCP Tools safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Using MCP Tools use?

Using MCP Tools is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Using MCP Tools use?

About 890 tokens (SKILL.md is roughly 3.6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Using MCP Tools?

Skills that share tags, products or a category with Using MCP Tools: MCP Server Builder (anthropics/skills, 180k stars), MCP Server Builder (shareAI-lab/learn-claude-code, 78k stars), MCP Integration for Plugins (anthropics/claude-plugins-official, 38k stars) and Crush Configuration (charmbracelet/crush, 29k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Using MCP Tools?

letta-ai (a GitHub organization) maintains it in letta-ai/letta-code, which has 3,562 GitHub stars. The repository holds 25 skills in this directory. The repository was last updated on October 10, 2026.

Source: letta-ai/letta-code on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.