HOI4 Agent Tools

HOI4 Agent Tools is an MCP server for coding agents to understand Hearts of Iron IV event chains, technology systems, AI weights, and MTTH timing and to inspect, create, or clean up focus trees, scripted GUIs, and maps. It produces source-linked structural and visual evidence that agents can use inside a larger modding workflow.

What it does

• Focus trees: inspect structure and references, render layouts, create trees, and reorganize existing branches.
• Scripted GUIs: trace GUI, GFX, scripted-GUI, and localisation links; render value-driven variants, dynamic country flags, inline text icons, states, resolutions, hierarchy, and click regions; diagnose alignment, visibility, clipping, panel containment, and button-label centering; create or repair interface source.
• Maps: navigate the complete rendered map by ID or localised name; inspect provinces, states, regions, adjacency, supply, railways, and positions; create states and provinces; change IDs; and repair connected map data.
• Event chains: scan definitions and call sites, trace routes and state flow, lint references, render graphs, and compare revisions without editing event source.
• Technology trees: reconstruct technology and doctrine paths, folder layouts, unlocks, bonuses, grants, metadata, assets, and structural changes.
• AI and MTTH: evaluate weighted choices and timing across explicit scenarios, bind special scope chains, enumerate dynamic target pools, sweep uncertain inputs, simulate distributions, compare patches, and analyze declared stateful pools.

Real results

The GUI renderer resolves the mod and installed-game sources, fonts, localisation colours, sprites, scripted visibility, dynamic values, lists, controls, and panel composition. These pairs show the in-game surface beside the MCP result.

Communist Insurgency in game	Communist Insurgency from MCP

Chaos Meter in game	Chaos Meter from MCP

The same scenario-aware renderer can select mutually exclusive settings panes and populate plausible runtime values.

Trigger Events settings	Advanced settings

The other workbenches return complete source-linked layouts and catalogs rather than prose-only summaries.

Focus tree	Technology tree

Map	Event chain	Probability ranking

Use from a coding agent

Requires Node.js 22.19 or later in the Node 22 line, or Node.js 24.

npm install --global hoi4-agent-tools@latest

[mcp_servers.hoi4_agent_tools]
command = "hoi4-agent-tools.cmd"

On non-Windows systems, use hoi4-agent-tools as the command. Agentic HOI4 repositories can include these steps in their agent template so the coding agent installs and registers the server itself; manual installation is not required in that workflow. Once connected, the server follows the active mod supplied by the client and the agent can call its HOI4 tools directly.

Tools

Set HOI4_AGENT_TOOLS_CHAOSX=1 on the server process to expose the optional chaosx.focus_country_assets and chaosx.visual_revision tools used by ChaosX workflows. They remain absent from the default public tool list.

Large outputs are linked hoi4-agent:// resources. For resources over 1 MiB, follow the continuationUri returned in _meta until it is null; clients may also request byte ranges with ?offset=<bytes>&length=<bytes>.

Coexistence with agent workflows

HOI4 Agent Tools provides HOI4 domain operations without replacing repository instructions such as AGENTS.md, skills, plans, or subagents. Its optional weighted-logic prompt helps an agent scope one probability analysis and then returns control to the normal workflow.

Connecting and listing tools does not scan mod source. Compact tool schemas and linked resources keep large diagnostics, renders, and diffs out of the agent's working context until needed. Event, technology, and probability tools analyze source without editing it; only hoi4.*_rewrite calls edit mod source.

Create or clean content

Ask your agent in normal task language. A typical workflow is inspect, render, rewrite, then inspect the result. The agent can call a raster tool when a pixel review is useful without paying that cost during every structural operation.