validate-mcp

validate-mcp is a skill for Claude Code from pdugan20/claudelint. It costs 74 tokens per session (303 once invoked), scanned A, original, MIT.

A configuration checker for .mcp.json files, which tell Claude Code how to connect to MCP servers and outside tools.

In plain words
What is it for?
It is for checking MCP server settings using the default file or a specified path, with optional detailed output and warnings treated as errors.
Why use it?
It finds invalid JSON, duplicate server names, unsupported connection types, bad URLs, command problems, and environment-variable issues before a connection fails.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Part of the claudelint plugin — 10 skills, 1 agent, 1 hook shipped together

Good fit It is for checking MCP server settings using the default file or a specified path, with optional detailed output and warnings treated as errors.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/pdugan20/claudelint/validate-mcp
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.

Any agent
npx skills add pdugan20/claudelint --skill validate-mcp
Clone the repo
git clone --depth 1 https://github.com/pdugan20/claudelint

Made for: Claude Code.

Or install claudelint, the plugin that ships this one along with the rest of its 10 skills, 1 agent, 1 hook.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for validate-mcp

README.md
[![agentmods](https://agentmods.dev/badge/skills/pdugan20/claudelint/validate-mcp/github.svg)](https://agentmods.dev/skills/pdugan20/claudelint/validate-mcp)
Your own site
<a href="https://agentmods.dev/skills/pdugan20/claudelint/validate-mcp"><img src="https://agentmods.dev/badge/skills/pdugan20/claudelint/validate-mcp/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for validate-mcp

Your own site · 80×15
<a href="https://agentmods.dev/skills/pdugan20/claudelint/validate-mcp"><img src="https://agentmods.dev/badge/skills/pdugan20/claudelint/validate-mcp.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 303 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00074 $0.00303
Opus 5 $0.00037 $0.00151
Sonnet 5 $0.00015 $0.00061
Haiku 4.5 $0.00007 $0.00030

Measured 8d ago against content hash f56b3d89e8b2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

validate-mcp 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 8d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (validate-mcp.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/validate-mcp/SKILL.md · 46 lines

What it actually says

Validate MCP Servers

Runs claudelint validate-mcp to validate .mcp.json configuration files.

Usage

claudelint validate-mcp $ARGUMENTS

Options

  • --path <path> - Custom path to .mcp.json
  • --verbose - Show detailed output
  • --warnings-as-errors - Treat warnings as errors

What Gets Validated

  • JSON syntax
  • Server name uniqueness and consistency
  • Transport type (stdio, sse)
  • Stdio transport (command validation)
  • SSE transport (URL validation)
  • Variable expansion patterns (${VAR}, ${VAR:-default})
  • Environment variables

Examples

claudelint validate-mcp
claudelint validate-mcp --path /path/to/.mcp.json

See Also

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 8d ago First seen · 46 lines · 74 tokens per session scan A f56b3d89e8b2

Subscribe to this mod's changes

validate-mcp is a skill published in the GitHub repository pdugan20/claudelint (12 stars, last pushed yesterday), licensed MIT. It adds 74 tokens to every session and 303 once invoked, about $0.0004 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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