# rails-ai-context **Your AI is guessing your Rails app. Every guess costs you time.** [](https://rubygems.org/gems/rails-ai-context) [](https://rubygems.org/gems/rails-ai-context) [](https://github.com/crisnahine/rails-ai-context/actions) [](https://registry.modelcontextprotocol.io)
[](https://github.com/crisnahine/rails-ai-context) [](https://github.com/crisnahine/rails-ai-context) [](https://github.com/crisnahine/rails-ai-context/actions) [](LICENSE)

The problem

You've seen it. Your AI:

• Writes a migration for a column that already exists — didn't check the schema
• Creates a method that duplicates one in a concern — didn't know it was there
• Uses the wrong association name — user.posts when it's user.articles
• Generates tests that don't match your patterns — factories when you use fixtures, or the reverse
• Adds a gem you already have — or calls an API from one you don't
• Misses before_action filters from parent controllers — then wonders why auth fails
• Invents a method that isn't in your codebase — then you spend 10 minutes finding out

You catch it. You fix it. You re-prompt. It breaks something else.

The real cost of AI coding isn't the tokens — it's the correction loop. Every guess is a round-trip: you catch it, you fix it, you re-prompt, and something adjacent breaks. This gem kills the guessing at its source.

Two commands. Problem gone.

gem "rails-ai-context", group: :development
rails generate rails_ai_context:install

Or standalone — no Gemfile needed

gem install rails-ai-context
cd your-rails-app
rails-ai-context init     # interactive setup
rails-ai-context serve    # start MCP server


Now your AI doesn't guess — it asks your app directly. 38 tools and 5 resource templates that query your schema, models, routes, controllers, views, and conventions on demand. Model introspection uses Prism AST parsing — every result carries a [VERIFIED] or [INFERRED] confidence tag so AI knows what's ground truth and what needs runtime checking.

See the difference


One call returns: definition + source code + every caller grouped by type + tests. Replaces 4-5 sequential file reads.

What stops being wrong

Real scenarios where AI goes sideways — and what it does instead with ground truth:

You ask AI to...	Without — AI guesses	With — AI verifies first
Add a subscription_tier column to users	Writes the migration, duplicates an existing column	Reads live schema, spots subscription_status already exists, asks before migrating
Call user.posts in a controller	Uses the guess; runtime NoMethodError	Resolves the actual association (user.articles) from the model
Write tests for a new model	Scaffolds with FactoryBot	Detects your fixture-based suite and matches it
Fix a failing create action	Misses inherited before_action :authenticate_user!	Returns parent-controller filters inline with the action source
Build a dashboard page	Invents Tailwind classes from memory	Returns your actual button/card/alert patterns, copy-paste ready
Trace where can_cook? is used	Reads 6 files sequentially, still misses callers	Single call: definition + source + every caller + tests

Verify it on your own app

Run these before and after installing to see what changes in *your* codebase: ```bash # Schema: does AI know what columns exist? rails 'ai:tool[schema]' table=users # Trace: find every caller of a method across the codebase rails 'ai:tool[search_code]' pattern=your_method match_type=trace # Model: associations, scopes, callbacks, concerns — all resolved rails 'ai:tool[model_details]' model=User # Controllers: action source + inherited filters + strong params in one shot rails 'ai:tool[controllers]' controller=UsersController action=create ``` Compare what AI outputs with and without these tools wired in. The difference is measured in *corrections avoided*, not bytes saved.

Three ways to use it

### MCP Server (stdio) AI calls tools directly via the protocol. Each AI tool gets its own config file — auto-detected on project open. ``` rails ai:serve ``` ``` → rails_search_code(pattern: "can_cook?", match_type: "trace") → rails_get_schema(table: "users") → rails_analyze_feature(feature: "billing") ```

### MCP Server (HTTP) Mount inside your Rails app — inherits routing, auth, and middleware. ```ruby # config/routes.rb mount RailsAiContext::Engine, at: "/mcp" ``` Native Rails controller transport. No separate process needed.

### CLI Same 38 tools, no server needed. Works in any terminal, any AI tool. ```bash rails 'ai:tool[search_code]' pattern="can_cook?" match_type=trace rails 'ai:tool[schema]' table=users rails 'ai:tool[analyze_feature]' feature=billing ```

Full Guide → — every command, every parameter, every configuration option.

Real-world examples

"Add a subscription field to users"

```bash rails 'ai:tool[schema]' table=users ``` ``` ## Table: users | Column | Type | Null | Default | |---------------------|---------|------|---------| | email | string | NO | [unique] | | subscription_status | string | yes | "free" | | created_at | datetime| NO | | ``` AI sees `subscription_status` already exists. Checks the model, then generates a correct migration — **first attempt**.

"Fix the broken cook creation flow"

```bash rails 'ai:tool[controllers]' controller=CooksController action=create ``` ``` # CooksController#create Filters: before_action :authenticate_user!, before_action :set_cook (only: show, edit) Strong params: cook_params → name, specialty, bio Renders: redirect_to @cook | render :new ``` AI sees the inherited `authenticate_user!` filter, the actual strong params, and the render paths. No guessing.

"Build a new dashboard view"

```bash # Check existing view patterns rails 'ai:tool[view]' controller=dashboard # → templates with ivars, Turbo frames, Stimulus controllers, partial locals # See existing components + usage examples rails 'ai:tool[component_catalog]' detail=standard # → ViewComponent/Phlex props, slots, previews, sidecar assets # Get Stimulus data-attributes rails 'ai:tool[stimulus]' controller=chart # → correct HTML with dashes (not underscores) + reverse view lookup ```

38 Tools

Every tool is read-only and returns data verified against your actual app — not guesses, not training data.

Search & Trace

| Tool | What it does | |:-----|:------------| | `search_code` | Trace: definition + source + callers + tests. Also: definition, call, class filters | | `get_edit_context` | Method-aware code extraction with class context |

Understand

| Tool | What it does | |:-----|:------------| | `analyze_feature` | Full-stack: models + controllers + routes + services + jobs + views + tests | | `get_context` | Composite: schema + model + controller + routes + views in one call | | `onboard` | Narrative app walkthrough (quick/standard/full) |

Schema & Models

| Tool | What it does | |:-----|:------------| | `get_schema` | Columns with indexed/unique/encrypted/default hints | | `get_model_details` | AST-parsed associations, validations, scopes, enums, macros — each result tagged `[VERIFIED]` or `[INFERRED]` | | `get_callbacks` | Callbacks in Rails execution order with source | | `get_concern` | Concern methods + source + which models include it |

Controllers & Routes

| Tool | What it does | |:-----|:------------| | `get_controllers` | Actions + inherited filters + render map + strong params | | `get_routes` | Code-ready helpers (`cook_path(@record)`) + required params |

Views & Frontend

| Tool | What it does | |:-----|:------------| | `get_view` | Templates with ivars, Turbo wiring, Stimulus refs, partial locals | | `get_stimulus` | HTML data-attributes (dashes!) + targets + values + actions | | `get_partial_interface` | What locals to pass + what methods are called on them | | `get_turbo_map` | Broadcast → subscription wiring + mismatch warnings | | `get_frontend_stack` | React/Vue/Svelte/Angular, Hotwire, TypeScript, package manager |

Testing & Quality

| Tool | What it does | |:-----|:------------| | `get_test_info` | Fixtures + relationships + test template matching your patterns | | `generate_test` | Test scaffolding matching your project's patterns | | `validate` | Syntax + semantic + Brakeman security in one call | | `security_scan` | Brakeman static analysis — SQL injection, XSS, mass assignment | | `performance_check` | N+1 risks, missing indexes, counter_cache, eager load candidates |

App Config & Services

| Tool | What it does | |:-----|:------------| | `get_conventions` | Auth checks, flash messages, create action template, test patterns | | `get_config` | Database, auth framework, assets, cache, queue, Action Cable | | `get_gems` | Notable gems with versions, categories, config file locations | | `get_env` | Environment variables + credentials keys (not values) | | `get_helper_methods` | App + framework helpers with view cross-references | | `get_service_pattern` | Interface, dependencies, side effects, callers | | `get_job_pattern` | Queue, retries, guard clauses, broadcasts, schedules | | `get_component_catalog` | ViewComponent/Phlex: props, slots, previews, sidecar assets |

Data & Debugging

| Tool | What it does | |:-----|:------------| | `dependency_graph` | Model/service dependency graph in Mermaid or text format | | `migration_advisor` | Migration code generation with reversibility + affected models | | `search_docs` | Bundled topic index with weighted keyword search | | `query` | Safe read-only SQL with timeout, row limit, column redaction | | `read_logs` | Reverse file tail with level filtering and sensitive data redaction | | `diagnose` | One-call error diagnosis with classification + context + git + logs | | `review_changes` | PR/commit review with per-file context + warnings | | `runtime_info` | Live DB pool, table sizes, pending migrations, cache stats, queue depth | | `session_context` | Session-aware context tracking across tool calls |

All 38 tools with parameters →  |  Real-world recipes →

Live Resources (VFS)

AI clients can also read structured data through resource templates — rails-ai-context:// URIs that introspect fresh on every request. Zero stale data.

Resource Template	What it returns
rails-ai-context://controllers/{name}	Actions, inherited filters, strong params
rails-ai-context://controllers/{name}/{action}	Action source code with applicable filters
rails-ai-context://views/{path}	View template content (path traversal protected)
rails-ai-context://routes/{controller}	Live route map filtered by controller
rails://models/{name}	Per-model details: associations, validations, schema

Plus 9 static resources (schema, routes, conventions, gems, controllers, config, tests, migrations, engines) that AI clients read directly.

Anti-Hallucination Protocol

Every generated context file ships with 6 rules that force AI verification before writing code. The protocol targets the exact cognitive failures that produce confident-wrong code: statistical priors overriding observed facts, pattern completion beating verification, stale context lies.

The 6 rules (shown to AI in every CLAUDE.md / .cursor/rules / .github/instructions)

1. **Verify before you write.** Never reference a column, association, route, helper, method, class, partial, or gem not verified in THIS project via a tool call in THIS turn. Never invent names that "sound right." 2. **Mark every assumption.** If proceeding without verification, prefix with `[ASSUMPTION]`. Silent assumptions forbidden. "I'd need to check X first" is a preferred answer. 3. **Training data describes average Rails. This app isn't average.** When something feels "obviously" standard Rails, query anyway. Check `rails_get_conventions` + `rails_get_gems` BEFORE scaffolding. 4. **Check the inheritance chain before every edit.** Inherited `before_action` filters, concerns, includes, STI parents. Inheritance is never flat. 5. **Empty tool output is information, not permission.** "0 callers found" signals investigation, not license to proceed on guesses. 6. **Stale context lies. Re-query after writes.** Earlier tool output may be wrong after edits. Enabled by default. Disable with `config.anti_hallucination_rules = false` if you prefer your own rules.

How it works

graph TD
    A["Your Rails App\nmodels + schema + routes + controllers + views + jobs"] -->|"31 introspectors"| B

    B["rails-ai-context\nPrism AST parsing · Cached · Confidence-tagged\nVFS: rails-ai-context:// URIs introspected fresh"]

    B --> C["MCP Server\nstdio / HTTP\n38 tools · 5 templates"]
    B --> D["CLI Tools\nRake / Thor\nSame 38 tools"]
    B --> E["Static Files\nCLAUDE.md · .cursor/rules/\n.github/instructions/"]

    style A fill:#4a9eff,stroke:#2d7ad4,color:#fff
    style B fill:#2d2d2d,stroke:#555,color:#fff
    style C fill:#0984e3,stroke:#0770c2,color:#fff
    style D fill:#00cec9,stroke:#00b5b0,color:#fff
    style E fill:#a29bfe,stroke:#8c83f0,color:#fff

Install

Option A — In Gemfile:

gem "rails-ai-context", group: :development
rails generate rails_ai_context:install

Option B — Standalone (no Gemfile entry needed):

gem install rails-ai-context
cd your-rails-app
rails-ai-context init

Both paths ask which AI tools you use (Claude Code, Cursor, GitHub Copilot, OpenCode, Codex CLI) and whether you want MCP or CLI mode. Each tool gets its own MCP config file — auto-detected on project open.

Commands

In-Gemfile	Standalone	What it does
rails ai:context	rails-ai-context context	Generate context files
rails 'ai:tool[NAME]'	rails-ai-context tool NAME	Run any of the 38 tools
rails ai:tool	rails-ai-context tool --list	List all available tools
rails ai:serve	rails-ai-context serve	Start MCP server (stdio)
rails ai:doctor	rails-ai-context doctor	Diagnostics + AI readiness score
rails ai:watch	rails-ai-context watch	Auto-regenerate on file changes

Documentation

Quickstart	5-minute getting started
Tools Reference	All 38 tools with every parameter
Recipes	Real-world workflows and examples
Custom Tools	Build and test your own MCP tools
Configuration	40+ config options with defaults
AI Tool Setup	Claude, Cursor, Copilot, OpenCode, Codex
Architecture	System design and internals
Introspectors	All 31 introspectors and AST engine
Security	4-layer SQL safety and file blocking
CLI Reference	Commands and argument syntax
Standalone	Use without Gemfile entry
Troubleshooting	Common issues and fixes
FAQ	Frequently asked questions

Build your own tools

Register custom MCP tools alongside the 38 built-in ones:

# app/mcp_tools/rails_get_business_metrics.rb
class RailsGetBusinessMetrics < MCP::Tool
  tool_name "rails_get_business_metrics"
  description "Key business metrics for this app"

  def call(period: "week")
    MCP::Tool::Response.new([{ type: "text", text: "Users this #{period}: #{User.recent.count}" }])
  end
end

# config/initializers/rails_ai_context.rb
config.custom_tools = [RailsGetBusinessMetrics]

Test with the built-in TestHelper (works with RSpec and Minitest):

include RailsAiContext::TestHelper

response = execute_tool("business_metrics", period: "month")
assert_tool_response_includes(response, "Users")

Custom Tools Guide →

Configuration

# config/initializers/rails_ai_context.rb
if defined?(RailsAiContext)
  RailsAiContext.configure do |config|
    config.ai_tools   = %i[claude cursor] # Which AI tools to generate for
    config.tool_mode  = :mcp              # :mcp (default) or :cli
    config.preset     = :full             # :full (31 introspectors) or :standard (17)
  end
end

All 40+ configuration options →

Observability

Every MCP tool call fires an ActiveSupport::Notifications event:

ActiveSupport::Notifications.subscribe("rails_ai_context.tools.call") do |event|
  Rails.logger.info "[MCP] #{event.payload[:method]} — #{event.duration}ms"
end

Requirements

• Ruby >= 3.2    Rails >= 7.1
• Optional: brakeman for security scanning, listen for watch mode, ripgrep for fast search

---

## About Built by a Rails developer with 10+ years of production experience.
1925 tests. 38 tools. 5 resource templates. 31 introspectors. Standalone or in-Gemfile.
MIT licensed. [Contributions welcome.](CONTRIBUTING.md)
If this gem saves you time, consider [sponsoring the project](https://github.com/sponsors/crisnahine).
[](LICENSE)