cl-mcp-server-dev

A contributor guide for cl-mcp-server, a Common Lisp server that provides tools for interacting with a Lisp read-eval-print loop (REPL). It covers the server’s structure, commands, tests, and coding rules.

In plain words
What is it for?
Use it to build, run, test, or modify the server and its 36 Common Lisp REPL tool handlers.
Why use it?
It helps developers understand which code handles communication and which code handles sessions, evaluation, and tools.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/quasi/cl-mcp-server/dev
Any agent
npx skills add quasi/cl-mcp-server --skill dev
Clone the repo
git clone --depth 1 https://github.com/quasi/cl-mcp-server

Made for: Claude Code, Codex.

Per session 26 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,877 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00026 $0.01877
Opus 5 $0.00013 $0.00938
Sonnet 5 $0.00005 $0.00375
Haiku 4.5 $0.00003 $0.00188

Measured 2d ago against content hash 1f9fe6587ba4, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

cl-mcp-server-dev 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 2d 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/skills/dev/SKILL.md · 178 lines

How it starts

The opening of the file, as written. The whole thing — 178 lines — stays where its author put it; the contents beside it link to each section on GitHub.

cl-mcp-server — Dev Skill

MCP server providing 36 Common Lisp REPL tools to Claude. Thin application layer over the cl-mcp protocol library.

Quick Reference

# Load
sbcl --load cl-mcp-server.asd --eval "(ql:quickload :cl-mcp-server)"

# Run
sbcl --load cl-mcp-server.asd \
     --eval "(ql:quickload :cl-mcp-server)" \
     --eval "(cl-mcp-server:start)"

# Test
sbcl --load cl-mcp-server.asd \
     --eval "(ql:quickload :cl-mcp-server/tests)" \
     --eval "(asdf:test-system :cl-mcp-server)"

Architecture

Dependency graph:

digraph {
  rankdir=LR
  "cl-mcp-server" -> "cl-mcp" [label="protocol"]
  "cl-mcp-server" -> "alexandria"
  "cl-mcp-server" -> "trivial-backtrace"
  "cl-mcp" -> "yason"
  "cl-mcp" -> "opsis/conditions"
}

What cl-mcp owns: JSON-RPC 2.0 framing, stdio transport, MCP handshake, per-server tool registry, error recovery.

What cl-mcp-server owns: Session state, code evaluation, 36 REPL tool handlers.

start reduces to 3 calls:

(cl-mcp:make-server :name "cl-mcp-server" :version "0.3.0")
(cl-mcp-server.tools:define-builtin-tools server session)
(cl-mcp:run-server server)

Package Structure

Package File Purpose
cl-mcp-server.conditions src/conditions.lisp REPL conditions + re-exports from cl-mcp.conditions
cl-mcp-server.error-format src/error-format.lisp Condition/backtrace formatting
cl-mcp-server.session src/session.lisp Persistent *package* context and state
cl-mcp-server.evaluator src/evaluator.lisp Safe evaluation with stream capture
cl-mcp-server.introspection src/introspection.lisp Symbol/class/method inspection
cl-mcp-server.asdf-tools src/asdf-tools.lisp ASDF/Quicklisp operations
cl-mcp-server.profiling-tools src/profiling-tools.lisp Statistical and deterministic profiling
cl-mcp-server.telos-tools src/telos-tools.lisp Telos intent introspection (graceful degradation; see RULE-007)
cl-mcp-server.tools src/tools.lisp Registers all 36 tools via cl-mcp:register-tool
cl-mcp-server src/server.lisp Entry point: start

Read the full file on GitHub · 178 lines

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. 2d ago First seen · 178 lines · 26 tokens per session scan A 1f9fe6587ba4

Subscribe to this mod's changes

cl-mcp-server-dev is a skill published in the GitHub repository quasi/cl-mcp-server (36 stars, last pushed 1mo ago), licensed MIT. It adds 26 tokens to every session and 1,877 once invoked, about $0.0001 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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