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.
npx agentmods add rules/jterratsdev/ableton-live-mcp/development-engineeringgit clone --depth 1 https://github.com/jterratsdev/ableton-live-mcpWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.01267 | $0.01267 |
| Opus 5 | $0.00633 | $0.00633 |
| Sonnet 5 | $0.00253 | $0.00253 |
| Haiku 4.5 | $0.00127 | $0.00127 |
Grade A, and why
development-engineering 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.
How it starts
The opening of the file, as written. The whole thing — 72 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Development Engineering
Developer work must start from the existing project shape, preserve the local architecture, and leave verifiable evidence that the changed production artifact works.
Project Context First
- Read the project manifest, build files, framework config, and existing module boundaries before generating code.
- Infer naming, layering, dependency direction, error style, logging style, and test conventions from nearby code.
- Do not introduce a new framework pattern, repository style, package layout, or dependency injection approach without a recorded architecture decision.
- Keep framework-specific adapters at the boundary. Domain and service code should remain portable where the product permits it.
- Before writing to an existing file, run a module-boundary check: current file size, responsibility, exported surface, and whether the new behavior belongs in domain, model, service, repository, or adapter code.
- Do not increase god-file risk. If a file is already large, multi-purpose, or adapter-shaped, prefer adding a focused module and wiring it from the existing entry point instead of adding more logic.
Entry Points And Layers
- Controllers, routes, commands, triggers, handlers, jobs, and webhooks must stay thin.
- Delegate business rules to services or domain modules, and delegate I/O to repositories, clients, gateways, or data-access modules.
- Keep request parsing, authorization, validation, orchestration, and persistence responsibilities separate enough that each can be tested directly.
- Public APIs and CLI commands must define request, response, errors, pagination, compatibility, and idempotency before implementation.
- Developer-owned code, scripts, generated options, and automation helpers that repeat collection values or process collections at scale must load the
collection-standardsskill. - CLI command modules should be nearly logicless: parse input, call one service or use-case, format output, and convert expected errors to user-safe messages. Business rules, workflow policy, persistence, retries, batching, and duplicated registries belong outside command modules.
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.
- yesterday First seen · 72 lines · 1,267 tokens per session scan A 9d774d70cd61
development-engineering is a cursor rule published in the GitHub repository jterratsdev/ableton-live-mcp (0 stars, last pushed 8d ago), licensed MIT. It adds 1,267 tokens to every session, about $0.0063 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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