MCPymol: Skill for Claude Code

.claude/skills/mcpymol-guide/SKILL.md

mcpymol-guide is a skill for Claude Code from chemrich/MCPymol. It costs 93 tokens per session (3,591 once invoked), scanned A, original, MIT.

A guide for using mcpymol, a server that controls PyMOL, a program for viewing and analyzing 3D protein structures.

In plain words
What is it for?
Fetching protein structures, inspecting sequences and contacts, comparing structures, rendering views, and exporting models for 3D printing.
Why use it?
It explains which tools and viewing settings to use, so structure questions can be answered with both measurements and clear images.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions Claude Code.

This is chemrich/MCPymol's own configuration. It tells Claude Code how to work on MCPymol itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything MCPymol configures →

Reuse

Borrowing it

Nothing to install: this file belongs to chemrich/MCPymol. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/chemrich/MCPymol/main/.claude/skills/mcpymol-guide/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/chemrich/MCPymol

Made for: Claude Code.

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 mcpymol-guide

README.md
[![agentmods](https://agentmods.dev/badge/skills/chemrich/mcpymol/mcpymol-guide/github.svg)](https://agentmods.dev/skills/chemrich/mcpymol/mcpymol-guide)
Your own site
<a href="https://agentmods.dev/skills/chemrich/mcpymol/mcpymol-guide"><img src="https://agentmods.dev/badge/skills/chemrich/mcpymol/mcpymol-guide/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 mcpymol-guide

Your own site · 80×15
<a href="https://agentmods.dev/skills/chemrich/mcpymol/mcpymol-guide"><img src="https://agentmods.dev/badge/skills/chemrich/mcpymol/mcpymol-guide.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 93 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,591 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 warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium analysis-evasion · line 1
    Suspicious Unicode normalization or mixed-script content
    Fix: Review the flagged content for security risks. Ensure no credentials, secrets, or sensitive data are exposed.
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 $0.00093 $0.03591
Opus 5 $0.00046 $0.01795
Sonnet 5 $0.00019 $0.00718
Haiku 4.5 $0.00009 $0.00359

Measured 9d ago against content hash 0f9c3ef5e67a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

mcpymol-guide 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 9d 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/mcpymol-guide/SKILL.md · 250 lines

How it starts

The opening of the file, as written. The whole thing — 250 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Driving the mcpymol MCP server

The mcp__mcpymol__* tools talk to a running PyMOL over a socket. Prefer the high-level tools (fetch_structure, the *_view presets, show/color/ select) over execute_pymol_command — the presets do coloring, transparency, H-bonds and labels in one call. Reach for execute_pymol_command only when no dedicated tool covers the need.

Report first, then draw

The presets make pictures; the report tools answer questions with numbers. When the user asks why or how much — what holds this ligand, how big is this interface, where do these differ — run the report and quote the numbers, then apply the matching view if a picture helps. Answering a quantitative question with only a rendering leaves the user to measure it themselves.

The question Reach for
What is this structure? structure_info
What is the sequence / numbering / where are the gaps? get_sequence
What contacts what, and how tightly? contact_report -> ligand_view
How big is this interface, which residues matter? interface_report -> interface_view
Where do two structures differ? superposition_view
How far / what angle / how much area? distance, angle, dihedral, sasa, rms_cur
Does my selection match anything? count_atoms
Occupancy / altloc / per-atom B-factor? atom_properties

contact_report classification is heavy-atom geometry (no hydrogens assumed): salt bridge <= 4.0 A, H-bond <= 3.5 A between N/O, hydrophobic <= 4.5 A, ring centroids <= 5.5 A. Report it as such — a "hydrogen bond" here is a donor-acceptor pair with plausible geometry, not one verified against a hydrogen. Aromatic detection covers the standard aromatic amino acids only; ligand rings appear as hydrophobic contacts.

interface_report gives buried surface area per side. Under ~400 A^2 usually means crystal packing rather than a real interface; over ~1000 A^2 means a substantial, likely specific association. Say which regime the number is in.

Read the full file on GitHub · 250 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. 9d ago First seen · 250 lines · 93 tokens per session scan A 0f9c3ef5e67a

Subscribe to this mod's changes

mcpymol-guide is a skill published in the GitHub repository chemrich/MCPymol (15 stars, last pushed 3d ago), licensed MIT. It adds 93 tokens to every session and 3,591 once invoked, about $0.0005 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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