opencode-ast-mcp AGENTS.md

Repository guidance for AI coding agents working on a Python MCP server that gives OpenCode tools for inspecting and changing code. It uses syntax-tree parsing, language models, and sandboxed tests.

In plain words
What is it for?
Use it when operating or contributing to the server, especially for code structure analysis, planning, patch generation, and test execution.
Why use it?
It explains which tools are safe in read-only planning mode and which require write-enabled build mode, reducing incorrect tool use.

Instructions file for CodexOpenCode

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 instructions/mathiasli152/opencode-ast-mcp/agents-md
Clone the repo
git clone --depth 1 https://github.com/maThiaslI152/opencode-ast-mcp

Made for: Codex, OpenCode.

Per session 2,846 This file is loaded in full into every session.
When invoked 2,846 The same file — it is already loaded in full.
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 $0.02846 $0.02846
Opus 5 $0.01423 $0.01423
Sonnet 5 $0.00569 $0.00569
Haiku 4.5 $0.00285 $0.00285

Measured yesterday against content hash 53b1273ac243, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

opencode-ast-mcp AGENTS.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 yesterday.

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.

AGENTS.md · 260 lines

How it starts

The opening of the file, as written. The whole thing — 260 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md — Guidance for AI Coding Agents

You are an AI agent working in this repo. Read this file in full before making changes. It documents the conventions, the MCP tools available to you, and the failure modes specific to this project.


Project at a glance

This is a Python MCP server that turns the OpenCode IDE into an agentic coding system. It exposes 9 tools backed by:

  • tree-sitter for AST extraction (Python / JS / TS)
  • LM Studio + Qwen 18B for local code analysis and log compression
  • OpenAI-compatible LLM brain (default: OpenRouter + Claude Haiku) for cloud SDD planning and patch generation
  • Podman for sandboxed test execution

You are likely operating through the MCP tools (from OpenCode) or on the MCP server code (as a contributor). These two modes have different guidance — see below.


If you are an OpenCode agent USING these tools

How the tools map onto OpenCode's plan/build mode

OpenCode itself has a plan mode (read-only) and a build mode (full write access). Of the 13 tools exposed by this server, only two are side-effecting and must wait for build mode:

  • ✅ Allowed in plan mode: get_file_skeleton, get_node, get_ast_json, list_files, get_project_overview, search_symbol, find_references, analyze_node, compress_log, get_loop_status, generate_sdd
  • ❌ Blocked in plan mode (use only in build mode): execute_in_sandbox, execute_autonomous_loop_tool

generate_sdd is the bridge between the two modes: it runs entirely in plan mode (no file writes), produces the SDD artifacts, and the user flips to build mode for the autonomous loop to walk through plan.md. The 4 codebase-awareness tools (list_files, get_project_overview, search_symbol, find_references) are also read-only and may be used freely in plan mode to scope the investigation before any code is written. See README.md → "How it works with OpenCode plan/build mode" for the full table.

Tool-selection rules (in priority order)

Read the full file on GitHub · 260 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. yesterday First seen · 260 lines · 2,846 tokens per session scan A 53b1273ac243

Subscribe to this mod's changes

opencode-ast-mcp AGENTS.md is an instructions file published in the GitHub repository maThiaslI152/opencode-ast-mcp (0 stars, last pushed 1mo ago), licensed MIT. It adds 2,846 tokens to every session, about $0.0142 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 2026-08-31.

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