ax-cpp-agent

A C++ guide for building AI agents with axllm, including tools, child agents, and MCP services.

In plain words
What is it for?
Use it when writing C++ agents that delegate work, call tools or MCP, require evidence citations, save learning, preserve state, or return structured results.
Why use it?
It reduces the need to work out the generated package’s agent patterns alone. It also covers citations, persistent learning, stage instructions, runtime state, and typed final responses.

Skill for Claude CodeCodex

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 skills/ax-llm/ax/ax-cpp-agent
Any agent
npx skills add ax-llm/ax --skill ax-cpp-agent
Clone the repo
git clone --depth 1 https://github.com/ax-llm/ax

Made for: Claude Code, Codex.

Per session 51 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 565 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 $0.00051 $0.00565
Opus 5 $0.00026 $0.00282
Sonnet 5 $0.00010 $0.00113
Haiku 4.5 $0.00005 $0.00056

Measured today against content hash 8ff35e2d0172, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ax-cpp-agent 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 today.

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.

packages/cpp/skills/ax-cpp-agent/SKILL.md · 49 lines

What it actually says

AxAgent For C++

This skill helps an agent write C++ code with the generated Ax package axllm. Use the generated package API, examples, and manifests; do not import TypeScript-only APIs unless you are editing the TypeScript package.

When To Use

  • Create an RLM agent with tools, child agents, or MCP clients.
  • Use clarification, discovery, recall, final, or respond envelopes.
  • Require evidence citations, attach a persistent playbook, or add stage-owned actor instructions.
  • Harvest run-end failures into the playbook and observe citation or playbook updates.
  • Skip the executor stage for no-tool tasks with a distiller respond envelope (directResponse, on by default).
  • Save and restore agent runtime state around long-running tasks.

Package Facts

  • Language: C++.
  • Package: axllm.
  • Package API docs: API.md and axir-api.json.
  • Capability manifest: axir-capabilities.json.
  • Runnable examples: examples/.
  • Real network support: yes.
  • Scripted no-key transport support: yes.
  • Runtime profiles: javascript-quickjs, python-pyodide.

Core Pattern

auto helper = axllm::agent("question:string -> answer:string");
auto out = helper.forward(llm, { {"question", "How should I proceed?"} });

Relevant API Surface

  • Agents And RLM: axllm::agent, axllm::AxAgent
  • MCP: axllm::AxMCPClient, axllm::AxMCPStreamableHTTPTransport, axllm::AxMCPStdioTransport
  • Runtime Profiles: axllm::ProcessCodeRuntime, axllm::RuntimeCapabilities, axllm::RuntimeEnvelope, javascript-quickjs, python-pyodide

Guardrails

  • Start from package examples for exact native syntax before inventing a new call shape.
  • Use provider-api examples only when the user explicitly has provider credentials available.
  • Use no-key examples for deterministic local checks and provider request mapping.
  • Treat AxIR as the source of generated package truth: if package docs disagree with source code, update the compiler and regenerate packages.
  • Do not copy repo-maintainer skills from tools/*/skills/ into user packages.
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. today Changed 8ff35e2d0172
  2. 2d ago First seen · 49 lines · 51 tokens per session scan A 1165978235bb

Subscribe to this mod's changes

ax-cpp-agent is a skill published in the GitHub repository ax-llm/ax (2,890 stars, last pushed yesterday), licensed Apache-2.0. It adds 51 tokens to every session and 565 once invoked, about $0.0003 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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