AIContextBuilder

AIContextBuilder (aicb)

Give coding agents a Roslyn-accurate map of your C#/.NET solution. aicb answers questions about callers, implementations, dependency injection, tests, side effects and change impact, then packs the relevant code into compact Markdown for an LLM. It runs locally as an MCP server and CLI; a Windows desktop app adds visual context selection, analysis and editing.

The software is closed source. This public repository contains its documentation, licence and releases. It is free for individuals, education and organizations below the licence thresholds.

See it answer a code question

Ask your coding agent:

What could be affected if I change ColorMixerService? Use AICB.

Or call the same tool from a terminal:

aicb call impact_of_change --sln C:/repo/App.sln --arg symbol=ColorMixerService

Abridged output from the bundled ColorMixer.SelectionLab sample:

{
  "symbol": "ColorMixerService",
  "resolvedKind": "type",
  "directCount": 1,
  "transitiveCount": 2,
  "risk": "low",
  "productionImpactCount": 2,
  "directImpact": { "items": ["DemoCompositionRoot"] }
}

The desktop app's MCP Usage page records calls locally and separates guided refusals from suspected defects:

That answer comes from the Roslyn symbol graph, not a substring search. AICB distinguishes overloads, follows interface and override relationships, understands partial types and records DI construction paths.

Where it helps

Question	Tool
Who calls or uses this?	find_usages
What is the blast radius of a change?	impact_of_change
Where is this interface implemented or overridden?	find_implementations, find_overrides
Which tests exercise this symbol?	find_tests_for
What gets injected here?	resolve_injection
Which code has side effects or calls an external API?	find_by_side_effects, calls_external
What context does an agent need for this task?	explain_symbol, prepare_task, pack_for_task

The desktop app turns code-quality, security, design and architecture findings into an actionable review queue:

AICB is most useful for non-trivial C#/.NET solutions and semantic questions that plain text search cannot answer reliably. It is not a general-purpose code search tool and does not analyze non-.NET projects. The first question opens and analyzes the solution, which can take seconds to minutes; later questions reuse the warm session.

Install

Install one form per machine:

You want	Install	Platform
MCP server and CLI	.NET global tool	Windows, Linux, macOS
Desktop app plus the same MCP server and CLI	Windows installer or portable ZIP	Windows

The .NET tool needs the .NET 8 SDK:

dotnet tool install -g AIContextBuilder
aicb --version

Update it later with dotnet tool update -g AIContextBuilder.

The Windows downloads are self-contained, but analyzing a solution still needs MSBuild from a .NET SDK or Visual Studio. The installer is not code-signed yet, so Windows SmartScreen displays a warning; every release provides SHA-256 checksums.

Connect a coding agent

Run this from the project you want the agent to work on:

aicb init

It writes the MCP configuration and the aicb-csharp-context agent skill without overwriting existing files. If it detects Claude Code, Codex or OpenCode project configuration, it also installs a symbol guard that blocks C# symbol searches by grep and redirects the agent to the semantic tool. This intentionally changes agent behaviour. Opt out with:

aicb init --hooks none

Client-specific status:

Client	MCP setup	Skill and guard
Claude Code	.mcp.json written by aicb init	Skill and optional guard installed
Codex	Add aicb mcp through the client's MCP configuration	Optional guard supported; skill location is not guessed
OpenCode	Add aicb mcp to opencode.json	Optional guard supported; skill location is not guessed
Cursor / Cline / other stdio clients	Add command aicb with argument mcp	Use the published skill if the client supports Agent Skills

Manual .mcp.json configuration for clients that read it:

{
  "mcpServers": {
    "aicb": {
      "command": "aicb",
      "args": ["mcp"]
    }
  }
}

Verify the connection by asking the client to call server_info. Every analysis tool accepts an absolute .sln, .slnx or .slnf path as its session, so no separate analyze step is required. See the five-minute guide for setup, first questions and troubleshooting.

Tool sets and Agent Skills

Set	Size	Purpose
Default MCP profile	54 tools	Curated semantic and structural tools for normal agent work
Full analysis profile	72 tools	Default set plus the measured long tail
Complete server surface	82 tools	Full profile plus opt-in infrastructure tools

Start the full analysis profile with aicb mcp --mcp-profile mcp-profile/full. Set AICB_MCP_TOOLS=all to add the infrastructure tools. The generated tool reference documents the default set; the MCP server manual documents all 82 tools and their parameters, and alongside them sessions and staleness, profiles, pools and facets, and what aicb init writes — twelve chapters in Markdown, readable in the browser and by an agent, and also published as a PDF.

Four Agent Skills ship in skills/:

• aicb-csharp-context routes semantic C# questions to the right tool.
• aicb-code-review checks a completed change for correctness.
• aicb-code-simplifier looks for unnecessary complexity.
• aicb-usage-check reports what this server was actually reached for.

The last three are opt-in: aicb init --skills=all.

CLI at a glance

aicb init      Connect a project to the MCP server and install the agent skill.
aicb analyze   Analyze a solution and emit context Markdown.
aicb export    Re-render Markdown from an existing session database.
aicb import    Import a constellation JSON.
aicb list      List built-in and custom profiles and presets.
aicb mcp       Start the stdio MCP server.
aicb call      Invoke one MCP tool without an MCP client.

Run aicb <command> --help for options.

Local by default

• The CLI and MCP server have no outbound network capability and do not modify the source code they analyze.
• There is no telemetry, analytics, update check, account or licence server.
• The desktop app sends context to an LLM only when you press Send to API; the endpoint may be a local model. Its Details tab is also a real editor and saves a file only when you explicitly use Save.
• Opening a solution runs its MSBuild logic to resolve references. Analyze only solutions you trust. AICB does not run third-party Roslyn analyzers or source generators.

A small number of explicitly named tools can write configuration or an export; their tool descriptions state this. The complete threat model and private reporting route are in SECURITY.md.

Licence at a glance

Use is free for:

• private, hobby and educational use by natural persons,
• accredited educational institutions for teaching, learning and non-commercial research,
• organizations that reach none of these thresholds: 100 employees, EUR 10 million annual turnover, 21 developers.

The thresholds apply to your organization, not to your clients. After first reaching any one threshold, you have 90 days to agree a commercial licence; use remains free during that period. Contact [e-mail]. There is no technical licence enforcement. Redistribution, modification, repackaging and competing products are not permitted. See the plain-language guide, LICENSE.txt and the full bilingual EULA.md.

Documentation and support

• Getting started — install, connect and ask the first question
• Tool reference — generated reference for the default MCP profile
• MCP server manual — the full reference in twelve Markdown chapters: connecting a client, aicb init, sessions and staleness, profiles and facets, every tool, troubleshooting
• General reference manual — the full reference in twelve Markdown chapters, with the printable PDF in the same folder
• Desktop app reference manual — the full reference in eleven Markdown chapters, with the printable PDF in the same folder
• Changelog and latest release

Questions and feature requests are welcome in GitHub Discussions. Report bugs through GitHub Issues; if GitHub does not offer a New issue button, use Discussions. Include aicb --version and, for MCP problems, the output of server_info. Report security issues privately as described in SECURITY.md.

"AIContextBuilder" and "AIContextBuilder for .NET" are unregistered trademarks of Gregor Dadera.