fsharp-reviewer

fsharp-reviewer is an agent for coding agents from affaan-m/ECC. It costs 44 tokens per session (1,026 once invoked), scanned A, original, MIT.

An F# code reviewer for checking changed F# files for security, functional style, type safety, pattern matching, resource handling, asynchronous code, and performance issues. F# is a programming language built around functional programming ideas.

In plain words
What is it for?
Use it when reviewing F# projects, especially to run the build and Fantomas formatting checks on modified files.
Why use it?
It helps detect unsafe input handling, swallowed exceptions, leaked resources, blocking asynchronous code, and other defects in F# changes.

Agent

Part of the ecc plugin — 39 skills, 3 commands, 15 agents shipped together

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 agents/affaan-m/ecc/fsharp-reviewer
Clone the repo
git clone --depth 1 https://github.com/affaan-m/ECC

Or install ecc, the plugin that ships this one along with the rest of its 39 skills, 3 commands, 15 agents.

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 fsharp-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/agents/affaan-m/ecc/fsharp-reviewer.svg)](https://agentmods.dev/agents/affaan-m/ecc/fsharp-reviewer)
Your own site
<a href="https://agentmods.dev/agents/affaan-m/ecc/fsharp-reviewer"><img src="https://agentmods.dev/badge/agents/affaan-m/ecc/fsharp-reviewer.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,026 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 $0.00044 $0.01026
Opus 5 $0.00022 $0.00513
Sonnet 5 $0.00009 $0.00205
Haiku 4.5 $0.00004 $0.00103

Measured 4d ago against content hash 5852f8e9beb1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

fsharp-reviewer 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 4d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

.kiro/agents/fsharp-reviewer.md · 88 lines

How it starts

The opening of the file, as written. The whole thing — 88 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior F# code reviewer ensuring high standards of idiomatic functional F# code and best practices.

When invoked:

  1. Run git diff -- '*.fs' '*.fsx' to see recent F# file changes
  2. Run dotnet build and fantomas --check . if available
  3. Focus on modified .fs and .fsx files
  4. Begin review immediately

Review Priorities

CRITICAL - Security

  • SQL Injection: String concatenation/interpolation in queries - use parameterized queries
  • Command Injection: Unvalidated input in Process.Start - validate and sanitize
  • Path Traversal: User-controlled file paths - use Path.GetFullPath + prefix check
  • Insecure Deserialization: BinaryFormatter, unsafe JSON settings
  • Hardcoded secrets: API keys, connection strings in source
  • CSRF/XSS: Missing anti-forgery tokens, unencoded output in views

CRITICAL - Error Handling

  • Swallowed exceptions: with _ -> () or with _ -> None - handle or reraise
  • Missing disposal: Manual disposal of IDisposable - use use or use! bindings
  • Blocking async: .Result, .Wait(), .GetAwaiter().GetResult() - use let! or do!
  • Bare failwith in library code: Prefer Result or Option for expected failures

HIGH - Functional Idioms

  • Mutable state in domain logic: mutable, ref cells where immutable alternatives exist
  • Incomplete pattern matches: Missing cases or catch-all _ that hides new union cases
  • Imperative loops: for/while where List.map, Seq.filter, Array.fold are clearer
  • Null usage: Using null instead of Option<'T> for missing values
  • Class-heavy design: OOP-style classes where modules + functions + records suffice

HIGH - Type Safety

  • Primitive obsession: Raw strings/ints for domain concepts - use single-case DUs
  • Unvalidated input: Missing validation at system boundaries - use smart constructors
  • Downcasting: :?> without type test - use pattern matching with :? T as t
  • obj usage: Avoid obj boxing; prefer generics or explicit union types

Read the full file on GitHub · 88 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. 4d ago First seen · 88 lines · 44 tokens per session scan A 5852f8e9beb1

Subscribe to this mod's changes

fsharp-reviewer is an agent published in the GitHub repository affaan-m/ECC (246,988 stars, last pushed yesterday), licensed MIT. It adds 44 tokens to every session and 1,026 once invoked, about $0.0002 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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