Borrowing it
Nothing to install: this file belongs to jovaneyck/fsi-mcp-server. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/jovaneyck/fsi-mcp-server/main/CLAUDE.mdgit clone --depth 1 https://github.com/jovaneyck/fsi-mcp-serverWrote 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.
[](https://agentmods.dev/instructions/jovaneyck/fsi-mcp-server/claude-md)<a href="https://agentmods.dev/instructions/jovaneyck/fsi-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/jovaneyck/fsi-mcp-server/claude-md/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.
<a href="https://agentmods.dev/instructions/jovaneyck/fsi-mcp-server/claude-md"><img src="https://agentmods.dev/badge/instructions/jovaneyck/fsi-mcp-server/claude-md.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00813 | $0.00813 |
| Opus 5 | $0.00407 | $0.00407 |
| Sonnet 5 | $0.00163 | $0.00163 |
| Haiku 4.5 | $0.00081 | $0.00081 |
Grade A, and why
fsi-mcp-server CLAUDE.md 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.
How it starts
The opening of the file, as written. The whole thing — 98 lines — stays where its author put it; the contents beside it link to each section on GitHub.
CLAUDE.md
This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
Project Overview
FSI MCP Server is a drop-in replacement for F# Interactive (fsi.exe) that adds Model Context Protocol capabilities. It wraps the standard F# Interactive process while maintaining full CLI compatibility and provides programmatic access via MCP tools.
Build and Development Commands
Essential Commands
# Build the entire solution
dotnet build
# Run the main FSI MCP Server (starts on http://0.0.0.0:5020)
dotnet run --project server
# Run with FSI arguments (all fsi.exe args are supported)
dotnet run --project server -- --nologo --define:DEBUG
# Build specific project
dotnet build server/fsi-mcp-server.fsproj
# Clean build artifacts
dotnet clean
Example Projects
# Run C# MCP example client
dotnet run --project mcp-csharp
# Run F# MCP example client
dotnet run --project mcp-fsharp
Testing and Debugging
# Test with MCP Inspector tool
npx @modelcontextprotocol/inspector
# Use scratch.fsx for manual F# Interactive testing
dotnet fsi scratch.fsx
Architecture Overview
Core Components
-
FsiService (
server/FsiService.fs): Core service that wrapsdotnet fsiprocess, manages I/O interception, and handles event queuing for both console and MCP inputs. -
FsiMcpTools (
server/FsiMcpTools.fs): Exposes MCP tools that provide programmatic access to FSI sessions:SendFSharpCode: Execute F# code in FSI sessionLoadFSharpScript: Load and execute .fsx filesGetRecentFsiEvents: Access FSI event history. No streaming supported yet.GetFsiStatus: Get session information
-
Program.fs: ASP.NET Core host that serves MCP endpoints with HTTP transport on
http://0.0.0.0:5020
Key Features
- Hybrid Usage: Supports simultaneous console input and MCP API calls
- CLI Compatibility: Complete drop-in replacement for
fsi.exe - Event System: Real-time streaming of FSI input/output via MCP (Server-Sent Events transport)
- Multi-source Tracking: Tracks input sources (console, API, file sync)
- Session State: Maintains persistent session state and event history
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.
- 9d ago First seen · 98 lines · 813 tokens per session scan A d37bb1af8b38
fsi-mcp-server CLAUDE.md is an instructions file published in the GitHub repository jovaneyck/fsi-mcp-server (40 stars, last pushed 8mo ago), licensed MIT. It adds 813 tokens to every session, about $0.0041 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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