Harness Adapters Agent Skill

Agent-only reference for firstmate harness operations.

Context cost
13.9k tokensestimated from the bundle, loaded when it triggers
Bundle
1 file · 55.7 kBtext throughout, nothing executable
Licence
not declarednone named by its author
Last change
—no release on file
Servers it uses
Noneruns standalone

What it does

Agent-only reference for firstmate harness operations. Use before spawning or recovering a crewmate or secondmate, handling a trust dialog, sending a harness-specific skill invocation, interrupting or exiting an agent, resuming an exited agent, or verifying a new harness adapter. Contains verified facts for claude, codex, opencode, pi, pi-signed, grok, kimi, and muse.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

agentproductivity

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md55.7 kB · preview
--- name: harness-adapters user-invocable: false metadata: internal: true ---
9# harness-adapters
10
11Use this reference before any harness-specific firstmate operation: spawn, recovery, trust-dialog handling, skill invocation, interrupt, exit, resume, or adapter verification.
12
13Crewmates default to the same harness firstmate is running on unless config/crew-harness records an adapter name.
14Optional dispatch profiles in config/crew-dispatch.json can override that static default for one crewmate or scout dispatch by selecting concrete harness, model, and effort axes at intake.
15When a matched rule or default is a profile array, load quota-array-dispatch for the completion-aware candidate choice after this skill establishes harness and model/provider facts.
16The captain may override that file at session start or later; a per-task instruction such as "run this one on codex" overrides it for that dispatch only.
17default means mirror firstmate's own harness.
18
19Secondmates have their own harness knob, so a secondmate can run on a different adapter than crewmates.
20config/secondmate-harness is the harness the primary uses to launch SECONDMATE agents, resolved through the fallback chain config/secondmate-harness -> config/crew-harness -> firstmate's own.
21An absent or default config/secondmate-harness therefore behaves exactly as the crew harness did before this knob existed (secondmates launched on the crew harness); setting it splits the two.
22The [secondmate-provisioning skill](../secondmate-provisioning/SKILL.md) owns the complete inherited-local-material allowlist and propagation contract.
23This skill owns only the harness-relevant consequence: a secondmate's own crewmates use the primary's inherited dispatch profiles and static harness value, while config/secondmate-harness is the primary's own setting and is never inherited - secondmates do not spawn secondmates.
24Inheritance copies the literal config/crew-harness file, so for a secondmate's own crewmates to run on the primary's crewmate harness the captain must set config/crew-harness to a concrete adapter name, such as codex.
25If config/crew-harness is unset or default, there is no concrete value to inherit, so the secondmate's own crewmates fall back to the secondmate's own/detected harness rather than the primary's effective crewmate harness.
26Inheritance also copies the literal config/crew-dispatch.json file, so secondmates apply the same best-fit profile rules for their own crewmates.
27
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md7,696 words
Files1
Licencenot declared
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈120
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
13,805
on trigger
The instruction body, read only when the skill fires.
7.0%
of a 200k window
Ten skills this size would take about 70% of the window before you open a file.
050k100k150k200k context window

13.9k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

1 file, 55.7 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md55.7 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 1 file you can review in full before installing.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Harness Adapters · 13.9k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/harness-adapters/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/harness-adapters" ] && { [ ! -e .claude/skills/harness-adapters ] || { mv .claude/skills/harness-adapters "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/harness-adapters" .claude/skills/ && echo "Installed .claude/skills/harness-adapters"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add karanmrn/harness-adapters

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/harness-adapters/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/harness-adapters/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/harness-adapters" ] && { [ ! -e ~/.claude/skills/harness-adapters ] || { mv ~/.claude/skills/harness-adapters "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/harness-adapters" ~/.claude/skills/ && echo "Installed ~/.claude/skills/harness-adapters" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/harness-adapters/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Versionnot versioned
Publishedno release date on file
PriceFree
Referencekaranmrn/harness-adapters

Versions

Its author publishes no version number, so there is nothing here to pin to: what you install is the folder as it stands today. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

Pinning

Nothing to pin to: this skill carries no version number of its own. What you install is what the folder holds on the day you install it.

Reviews

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