Two design skills · both proven

crypto-protocol-diagram vs mcp-builder

Both skills were run through Claude twice: once on a fixed brief without the skill, once with it. The briefs differ because each is written for the job the skill claims to do, so compare each skill against its own baseline, then decide which difference matters for your work.

crypto-protocol-diagram

Extracts protocol message flow from source code, RFCs, academic papers, pseudocode, informal prose, ProVerif (.pv), or Tamarin (.spthy) models and generates Mermaid sequenceDiagrams with cryptographic annotations. Use when diagramming a crypto protocol, visualizing a handshake or key exchange flow, extracting message flow from a spec or RFC, diagramming a ProVerif or Tamarin model, or drawing…

Category: Design
Source: trailofbits/skills
License: Other
Proof model: claude-opus-5-5
Brief: “Draw the message flow of this login protocol as a single HTML page with an SVG sequence diagram, and note any weaknesses. 1. Client sends username to server. 2. Server replies with a random 16-byte nonce and the user's salt. 3. Client computes H = SHA-256(salt || password) and sends HMAC-SHA256(key=H, msg=nonce). 4. Server looks up stored H, computes the same HMAC and compares. 5. On success the server returns a session token valid for 30 days.”
Skill commit: 2be6433

Without the skillWith crypto-protocol-diagram

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Without, runWith crypto-protocol-diagram, run3 independent runs per side, none selected by hand.

Download the with-skill page

mcp-builder

Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).

Category: Design
Source: anthropics/skills
License: Not stated
Proof model: claude-opus-5-5
Brief: “Build an MCP server in TypeScript that gives an agent read access to a team's Linear-style issue tracker through a REST API: tools to search issues, get one issue with comments, and list a project's open issues by priority. Present it as a single HTML page with the full source of each file, the tool schemas, how errors and pagination are handled, and how to run and connect it.”
Skill commit: dbd4588

Without the skillWith mcp-builder

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Without, runWith mcp-builder, run3 independent runs per side, none selected by hand.

Download the with-skill page

We don’t pick a winner for you: the pages are the evidence. Both proofs can be repeated with the brief, model and commit shown above. See alternatives to crypto-protocol-diagram or alternatives to mcp-builder.