# Aster Capabilities > Everything Aster can do - Skill: `zfinix/aster-capabilities` (Agent Skill) - Install (CLI): `npx skillmds@latest add zfinix/aster-capabilities` - Raw SKILL.md: https://api.skillmd.com/api/skills/zfinix/aster-capabilities/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Coding & Dev Tools - Author: zfinix (https://skillmd.com/u/zfinix) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/zfinix/aster-capabilities --- # Everything Aster can do Aster is a self-hostable agent harness for software work: one `aster` binary that chats, edits, runs commands, reviews diffs, remembers, and runs on a schedule, in a terminal, a browser, VS Code, Zed, or a desktop window. Every subcommand takes `--json` (before or after it) and turns errors into `{"ok":false,"error":…}`. Every command that runs a model takes `--model` and `--effort off|low|medium|high|xhigh|max|ultra`. When a question is "can Aster do X", find X below and answer with the command. When unsure whether a flag still exists, run `aster --help`; it is the source of truth. ## Install, upgrade, sign in ```sh curl -fsSL https://withaster.dev/install | sh # binary install cargo install --path crates/aster-cli # from source, Rust 1.85+ aster upgrade # swap in the latest release aster upgrade --version 0.4.0 --force # pin or reinstall aster init # wizard: provider + key into ~/.aster aster init --local # config in this repo instead aster init --yes --force # default aster.yaml, no questions aster login # GitHub (for --pr and --comment) aster login codex | openrouter | zai # provider sign-in via browser aster logout # drop every stored login aster status # what the next turn runs with aster announce [--dismiss id,id] # undismissed release notes as JSON ``` Config lives in `./aster.yaml` (repo) merged over `~/.aster/aster.yaml`; keys live in `.env` files, never in yaml. Precedence: CLI flags > env > aster.yaml > defaults. ## Chat ```sh aster # TUI in the current repo aster "why does the build fail?" # one-shot, prints and exits (--print / -p) echo "explain this repo" | aster # piped stdin is the prompt aster --continue # resume this repo's latest session aster --resume [ID] # pick a session, or resume one by id aster --session ID "next question" # persist into a named session aster --messages-json history.json # caller owns the transcript (- for stdin) aster --compact --messages-json h.json # fold history into a summary, print it aster --stream # NDJSON events out, approval replies in aster --no-tools # plain chat, no read/search/edit aster --no-mcp # start instantly; /mcp connects later aster --allow-edits # let a scripted turn edit files aster --permission-mode plan|manual|auto|edit|yolo ``` Chat works outside a repo too, with less to look at. ### Keys in the TUI | Key | Does | | --- | --- | | `enter` | Send; while a turn runs it queues the message | | `esc` | Interrupt the running turn; `esc esc` quits | | `shift+tab` | Step to the next permission mode | | `ctrl+j` | Newline without sending | | `ctrl+o` | The `/switch` panel | | `@` | Mention a repo file (images and documents attach as content) | | `↑ ↓` | Move the cursor, then step through past messages | ### Slash commands | Command | Does | | --- | --- | | `/switch` | Thinking, mode, effort, model, provider in one panel | | `/model [id]`, `/m` | Switch model or open the picker | | `/provider [id\|url]`, `/p` | Switch endpoint, then pick a model | | `/mode [name]` | plan, manual, auto, edit, yolo | | `/effort [level]` | Set or cycle the reasoning budget | | `/thinking` | Print the model's thinking in full or not | | `/yolo` | Toggle yolo (guardrails off, red theme) | | `/mom [resume]` | Show the mom.yaml policy state; `resume` re-arms it after a manual `/model` | | `/resume`, `/r` | Reopen a saved session | | `/clear`, `/c` | Start fresh | | `/compact` | Fold earlier turns into a summary | | `/status` | Session, model, context, token usage | | `/diff`, `/d` | Uncommitted changes | | `/mcp` | MCP servers and their tools; connects them if `--no-mcp` skipped it | | `/skills` | Pick a skill to load | | `/memory` | What Aster remembers here | | `/theme` | Dark or light | | `/welcome` | Show or hide the session header, saved to `ui.welcome` | | `/goal ` | Loop turns until a separate judge model says the condition is met (see Goals) | | `/help`, `/quit` | The list above; exit | Installed skills that declare a command also appear as slash commands (for example `/write-tests`). ## Permission modes and rules One setting gates edits and commands: `shift+tab` in chat, `--permission-mode` per run, `permissions.mode` in aster.yaml. | Mode | Does | | --- | --- | | `plan` | Explore and present a plan. Never edits or runs | | `manual` | Ask before every edit and command (denies when headless) | | `auto` | Edit and run, pause on risky commands (sudo, rm, curl, ssh…) | | `edit` | Like auto but commands are trusted; only a rule stops one. Default | | `yolo` | No rules, no sandbox. Asks first | Rules use one language for all tools, precedence deny > ask > allow > built-ins > mode: ```yaml permissions: mode: edit allow: ["Bash(cargo test:*)", "Edit(src/**)", "Read(**/.env)"] ask: ["Edit(migrations/**)", "Bash(git push:*)"] deny: ["Bash(npm publish:*)", "Edit(infra/**)"] use_default_rules: true # asks on .git/**, workflows, hooks; refuses secrets additional_directories: ["~/Downloads"] # readable outside the repo without asking allow_credentials: ["gh:~/.config/gh"] # sandbox credential dirs a command may read ``` A `Bash` rule matches inside `bash -lc "…"` too. Outside yolo, commands run in a sandbox: writes limited to the repo and temp, secrets stripped from the environment, network on with per-domain approval. ## What the agent can do inside a turn These are the tools the model calls. Knowing them tells you what to ask for. | Tool | Does | | --- | --- | | `read_file` | Read with line numbers, optional `start_line`/`end_line`. PDF, Word, PowerPoint, Excel, ODF, EPUB, RTF convert to Markdown. Outside-repo and `~` paths prompt | | `list_files`, `find_files`, `search_files` | Directory listing, glob search, regex content search (smart-case, grouped by file) | | `explore` | Several lookups in one call | | `edit_file` | Search-and-replace edits, gated by the permission mode | | `ast_grep`, `ast_edit` | Structural search and rewrite over syntax trees | | `lsp_definitions`, `lsp_references`, `lsp_diagnostics` | Language-server navigation and errors | | `run_command`, `run_tests` | Shell in the sandbox (timeout `agent.command_timeout_secs`); the test runner | | `agent` | Spawn sub-agents from the roster (see Sub-agents) | | `ask_user` | Structured question with options | | `update_plan`, `exit_plan_mode` | Visible step plan; the plan-mode approval handshake | | `remember`, `recall`, `forget` | Durable memory (see Memory) | | `read_skill` | Load a skill's body on demand | | `open_preview` | Open a URL or file in the browser (`ASTER_NO_BROWSER=1` prints the URL instead) | | `security_scan` | Static security scan of the working tree | | MCP tools | Anything a configured server exposes, injected progressively; `web/search` and `web/extract` ship built in | Limits: `agent.max_tool_rounds` (60), `agent.command_timeout_secs` (300), `agent.compact_budget_chars` (192000), `agent.max_output_tokens` (8000), `agent.language` (the user's), env `ASTER_MAX_TOOL_ROUNDS`, `ASTER_COMMAND_TIMEOUT`, `ASTER_COMPACT_BUDGET`, `ASTER_MAX_TOKENS`, `ASTER_LANGUAGE`. ## Review Hypothesize, retrieve evidence from a local symbol index, verify by trying to refute, shape. Findings carry file, line, severity, category, title, suggestion, confidence. ```sh aster review # current branch aster review --range main..HEAD git diff HEAD~1 | aster review --diff - aster review --pr 42 [--repo owner/repo] [--token T] aster review --pr 42 --comment [-y] # post inline PR comments aster review --tui # browse findings aster review --json # data for CI aster review --stream # NDJSON progress for UIs aster review -i "src/**/*.rs" -x "**/*.lock" --min-confidence 0.6 aster review --no-index # faster, less evidence aster review --effort high ``` Config under `review:` in aster.yaml: `model`, `hypothesis_model`, `verify_model`, `base_url`, `min_confidence`, `max_diff_bytes`, `analyzers: [semgrep, ast-grep]`, `astgrep_rules`, `effort`, `web_search`, `focus_areas`, `include`, `exclude`. `model: auto` picks from OpenRouter's live rankings (`ASTER_ROUTER_TIER=cheap|balanced|strong`, see `aster model router`). Env: `ASTER_VERIFY_MODEL`, `ASTER_HYPOTHESIS_MODEL`, `ASTER_VERIFY_CONCURRENCY`. ## Fix ```sh aster review --json | aster fix # dry run: preview the patches aster review --json | aster fix --apply # write them aster fix --findings-json findings.json --apply --repo-root . ``` ## Sessions Every chat, ACP thread, and scheduled run is a session under `~/.aster`. ```sh aster sessions [list] [--all] # this repo, or every project aster sessions show ID aster sessions rename ID "title" aster sessions delete ID aster sessions prune [--keep N] [--older-than DAYS] # empties always go aster sessions import [--from claude|codex|cursor|opencode|hermes] [--dry-run] ``` ## Memory Two layers: short project facts always in context, named blocks listed by title and read on demand. The agent writes with `remember`, reads with `recall`, retracts with `forget`. ```sh aster memory [list] aster memory add "we deploy from release, never main" aster memory add "prefers terse replies" --title tone aster memory show tone aster memory remove tone ``` ## Config, keys, provider, model ```sh aster config # form in a terminal, table when piped aster config list | get KEY | set KEY VALUE [--global|--local] | unset KEY aster config path | edit [--global|--local] aster config providers | provider [ID --model M] | models [--capabilities] | model [ID] aster config keys [--all] | key [VAR [VALUE]] [--local] aster key list [--all] | get VAR | set VAR [VALUE] [--stdin] [--local] | unset VAR | path aster provider list aster provider use openai [--model gpt-5.5] # endpoint and model together aster model list [--capabilities] | use ID | recommended aster model router [--tier cheap|balanced|strong] ``` Any OpenAI-compatible endpoint works. A key var named for the endpoint (`ANTHROPIC_API_KEY`, `OPENROUTER_API_KEY`) beats the shared `ASTER_API_KEY`. `ASTER_MODEL` and `ASTER_BASE_URL` in the shell outrank the file and are reported when set. ## mom.yaml: model routing per turn Drop `mom.yaml` in the repo root or `~/.aster/`. Entries describe intent (`power`, `thinking`, `prefer`), `switch` rules fire on conditions like `planning`, `stuck`, `looping`, `model-down`, and a cheap router judges the rest. Switches show as `mom:` notes in chat. ```sh aster mom check # validate, show what each entry resolves to aster mom route "refactor the auth module" # which entry the router would pick ``` Spec: `specs/mom.md`. Logs: `~/.aster/logs/mom-router.jsonl`, `mom-switches.jsonl`. ## Skills Folders with a `SKILL.md`; titles are indexed, bodies load when relevant. Five core skills are built in and listed; eleven more about the agent's own conduct are internal and never shown. A skill installed under `/internal//` is internal too. Ten optional skills are bundled off by default; `aster skills bundled` marks the internal ones, which install into `internal/`. ```sh aster skills list [-p|-g] aster skills add owner/repo | git-url | ./dir | claude-code|cursor|… [-p] [-s name] [--all] [-y] [--force] [-l] aster skills add # wizard listing skills found on this machine aster skills find react [--owner org] # search GitHub, install interactively aster skills use owner/repo@skill # print a skill without installing aster skills bundled [name…] [--force] # list or turn on optional built-ins aster skills update [name…] aster skills remove [name…] [--all] [-y] aster skills init my-skill # scaffold my-skill/SKILL.md ``` Skills you write are installed right after writing (`aster skills add ./dir --all --yes --force`), not saved to memory. Format rules: `aster-skill-authoring`. ## Plugins Agent Plugins packages (skills plus MCP servers) install unchanged; their servers appear as `/`. ```sh aster plugins add owner/repo | ./dir [-p] [--plugin name] [--all] [-y] [-l] [--force] aster plugins list [-p|-g] aster plugins remove name [--purge] [-y] aster plugins validate [./dir] ``` ## MCP servers Declared under `mcp.servers` in aster.yaml: `command`+`args`+`env` for local, `url` (+`headers`, `type: sse`) for remote. Tools are injected progressively within `mcp.context_tokens` / `mcp.inventory_percent`; `mcp.tools.allow|deny` filter by `server/tool` with globs. WebMCP bridges tools a page registers in your own Chrome (`mcp.webmcp`, Chrome started with `--remote-debugging-port=9222`). ```sh aster mcp list [--no-connect] aster mcp enable NAME | server/tool aster mcp disable NAME | server/tool # globs allowed aster mcp import [--from claude|codex|cursor|opencode|hermes] aster mcp remove [NAME] aster mcp login NAME # OAuth for a remote server ``` ## Web as Markdown `search` and `extract` need no key. `crawl` needs `FIRECRAWL_API_KEY`, `CONTEXT_DEV_API_KEY`, or the Cloudflare pair; `sitemap` and `screenshot` need `CONTEXT_DEV_API_KEY`. `aster key list --all` shows every web key and what it buys. The same five are the agent's `web/*` tools. ```sh aster web search "query" [--limit 5] [--region us-en] [--safesearch strict] aster web extract https://… aster web crawl https://… [--max-pages 100] [--max-depth N] [--url-regex R] [--main-content-only] [--follow-subdomains] [--no-pdfs] [--stop-after-ms 80000] aster web sitemap docs.rs [--max-links 500] [--url-regex R] aster web screenshot https://… [--full-page] ``` ## Sub-agents and headless runs The `agent` tool fans work out to personas: `scout` (read-only recon), `cartographer` (architecture mapping), `sentinel` (skeptical review), `forge` (applies a described change), `scribe` (docs only), `prism` (synthesis of collector reports). Custom agents are an `AGENT.md` directory; see `docs/SWARM.md`. Limits under `agents:` (`max_concurrent`, `max_per_turn`, `agent_timeout_secs`, `collector_model`). ```sh aster run sentinel "review yesterday's commits on main" [--notify] [--cwd DIR] [--schedule NAME] ``` `aster run --help` mentions `aster agents`; that command does not exist, the roster above is the list. ## Scheduled runs and reminders ```yaml schedules: - name: nightly-review cron: "0 9 * * *" # five fields, local time agent: sentinel task: "review yesterday's commits on main" notify: true ``` ```sh aster cron install | list | remove NAME | run NAME # launchd on macOS, cron on Linux aster remind "stand up" "in 30m" # or "in 2h", "at 18:00" ``` ## Remote control over Telegram ```sh ASTER_TELEGRAM_TOKEN=… ASTER_REMOTE_USERS=123,456 aster remote telegram [--mode manual] aster remote telegram --token T --user 123 --mode auto ``` Long-polling, no public URL. Approval prompts arrive as buttons. A message sent while it is working joins the turn in flight instead of starting a second one, so it hears you mid-task; one that lands as the turn ends runs next. ## Goals: loop until a judge agrees In chat, `/goal ` keeps the turn loop running; after each turn a separate cheap judge model rules `met`, `not_yet`, or `impossible`, so the worker never certifies itself. `ASTER_GOAL_MAX_TURNS` caps the loop (default 20). ## Surfaces | Surface | How | | --- | --- | | Terminal | `aster` | | Browser | `aster serve [--port 8080] [--host 0.0.0.0] [--no-open]`; default `http://localhost:4187`, token in the URL off loopback | | VS Code / Cursor | `editors/vscode` extension: sidebar, tab, or window; `cmd+shift+a` opens, `cmd+alt+k` command menu, `cmd+alt+n` new, `cmd+alt+r` reopen, `alt+a` sends the selection as an @-mention; review findings into the Problems pane; settings `aster.binaryPath`, `aster.minConfidence`, `aster.publishDiagnostics`, `aster.extraArgs` | | Zed | `aster acp [--permission-mode M] [--model M] [--no-mcp] [--trace]` as a custom agent server in `settings.json` | | Desktop | `desktop/` Tauri app around the same CLI | All surfaces resolve model, provider, mode, and keys from the same aster.yaml, so `provider use` switches everywhere at once. ## Environment-only knobs `ASTER_API_KEY`, `ASTER_BASE_URL`, `ASTER_MODEL`, `ASTER_EFFORT`, `ASTER_MAX_TOKENS` (`off` lifts the cap), `ASTER_SEED`, `ASTER_TIMEOUT_SECS`, `ASTER_MAX_RETRIES`, `ASTER_DEADLINE_SECS`, `ASTER_WEB_SEARCH=1`, `ASTER_NO_BROWSER`, `ASTER_NO_UPDATE_CHECK`, `ASTER_EDITOR`, `ASTER_UI_DIR`, `ASTER_MCP_EXTRA`, `ASTER_VISION_MODEL`, `ASTER_ASTGREP_RULES`, `ASTER_PRICE_PROMPT_PER_M`, `ASTER_PRICE_COMPLETION_PER_M`, `OTEL_EXPORTER_OTLP_ENDPOINT`. `.env.example` lists them with notes. ## When something fails ```sh aster status # what will run, and from where tail -5 ~/.aster/logs/provider-errors.jsonl | jq # every failed provider request aster config list # each setting and its source aster mcp list --no-connect # servers without spawning them ``` ## Where to read more `docs/CONFIG.md` (every key), `docs/MCP.md`, `docs/MEMORY.md`, `docs/SWARM.md`, `docs/PLUGINS.md`, `docs/ALGORITHM.md` (review), `docs/ANALYZERS.md`, `specs/mom.md`. Sibling skills go deeper on one area: `aster-cli`, `aster-config`, `aster-chat-sessions`, `aster-review-ci`, `aster-fix-workflow`, `aster-planning`, `aster-skill-authoring`.