Agent skill

Predicate

by zalando in zalando/skipper

Create or modify code in the predicates package and all its sub-folders

MITAuto-check passedDevOps & Cloud

Install Predicate

skills CLI
$ npx skills add zalando/skipper --skill predicate -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install zalando/skipper predicate --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/zalando/skipper.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/predicate .claude/skills/predicate && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
predicate
GitHub stars
3.3k
Token cost
~453 tokens
SKILL.md length
160 words
Files
1
Skills in repo
5
Repo updated
First seen
Licence
MIT

At a glance

Create or modify code in the predicates package and all its sub-folders

  • DevOps & Cloud work in your project
  • SKILL.md covers What I do, When to use me and Quick start
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Predicate is an agent skill from zalando/skipper. Create or modify code in the predicates package and all its sub-folders

Its SKILL.md is about 450 tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts. Compatibility notes: opencode, claude

It sits in DevOps & Cloud. It works with Kubernetes. The repository describes itself as: An HTTP router and reverse proxy for service composition, including use cases like Kubernetes Ingress. The licence is MIT.

When your agent uses it

  • DevOps & Cloud work in your project

Example prompts

  • “/predicate”

Requirements

  • Compatibility (from SKILL.md): opencode, claude

What it can do on your machine

Read from SKILL.md and the folder at commit 4f6cd0a. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are go).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

  • Compatibility

    opencode, claude

    From compatibility in the SKILL.md frontmatter.

Context cost

Predicate loads about 453 tokens when it runs. Until then it costs about 20 tokens; SKILL.md has 160 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~20
When it runs · the whole SKILL.md, loaded when a task matches
~453

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from zalando/skipper at commit 4f6cd0a, republished under its MIT licence (© zalando). 160 words, ~453 tokens.

Download SKILL.mdSave it as .claude/skills/predicate/SKILL.md (or your agent's skills folder).
name
predicate
description
Create or modify code in the predicates package and all its sub-folders
compatibility
opencode, claude
license
MIT
metadata.audience
maintainers, contributors

What I do

  • Create predicate code that is efficient and readable

When to use me

Use this when you are writing code in sub-folders of ./predicates/. Some predicates are also located in the ./routing/ folder for historical reasons.

Quick start

A predicate consists of 2 types spec and predicate that implement 2 different interfaces:

go
// PredicateSpec instances are used to create custom predicates
// (of type Predicate) with concrete arguments during the
// construction of the routing tree.
type PredicateSpec interface {

	// Name of the predicate as used in the route definitions.
	Name() string

	// Creates a predicate instance with concrete arguments.
	Create([]any) (Predicate, error)
}
go
// Predicate instances are used as custom user defined route
// matching predicates.
type Predicate interface {

	// Returns true if the request matches the predicate.
	Match(*http.Request) bool
}

The Create([]any) (Predicate, error) function is run at routing tree creation time, so only once in a while. Everything we can pre-compute to run a faster Match(*http.Request) bool execution the better. Here we process input from developers or operators that might do mistakes. We want to show errors clearly.

The Predicate interface function Match(*http.Request) bool is running in the hotpath of the request processing. Here we need to be very efficient and want to reduce latency, increase throughput, minimize allocations and we run heavily concurrent. Every request will be proceesed by a lot of Predicates and so each Match needs to be as fast as possible.

© zalando, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/predicate of zalando/skipper.

Open the folder on GitHubat commit 4f6cd0a

Compare with similar skills

Predicate next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Predicate compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Predicate this skillzalando/skipper3.3k—~453Automated safety check: PassMIT
KubeSphere Multi-Tenant Managementkubesphere/kubesphere17k1 repos~3.1kAutomated safety check: PassCustom licence
Azure Diagnosticsmicrosoft/azure-skills1.5k1 repos~1.6kAutomated safety check: PassMIT
Kubeshark Installerkubeshark/kubeshark12k—~3.6kAutomated safety check: NotesApache-2.0
Sim Helmsimstudioai/sim30k—~2.2kAutomated safety check: PassApache-2.0
Helm Chart ScaffoldingCybereason-Public/owLSM28013 repos~381Automated safety check: PassGPL-2.0

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Works with

Categories

Questions about Predicate

What does Predicate do?

Create or modify code in the predicates package and all its sub-folders. Predicate is an agent skill from zalando/skipper.

When should I use Predicate?

Predicate fits situations like: devOps & Cloud work in your project.

How do I install Predicate in Claude Code?

Run `npx skills add zalando/skipper --skill predicate -a claude-code`. Or copy the skill folder (.agents/skills/predicate in zalando/skipper) into .claude/skills/predicate in your project. Claude Code loads it when a task matches its description.

How do I install Predicate in Codex?

Run `npx skills add zalando/skipper --skill predicate -a codex`. Or copy the skill folder (.agents/skills/predicate in zalando/skipper) into .agents/skills/predicate in your project. Codex loads it when a task matches its description.

Can I use Predicate in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add zalando/skipper --skill predicate -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/predicate, .gemini/skills/predicate, .github/skills/predicate and .opencode/skills/predicate in your project.

What does Predicate need to run?

SKILL.md names no scripts, command-line tools or credentials: Predicate is instructions for the agent only. Compatibility (from SKILL.md): opencode, claude.

Does Predicate access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Predicate safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Predicate use?

Predicate is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Predicate use?

About 453 tokens (SKILL.md is roughly 1.8k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Predicate?

Skills that share tags, products or a category with Predicate: KubeSphere Multi-Tenant Management (kubesphere/kubesphere, 17k stars), Azure Diagnostics (microsoft/azure-skills, 1.5k stars), Kubeshark Installer (kubeshark/kubeshark, 12k stars) and Sim Helm (simstudioai/sim, 30k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Predicate?

zalando (a GitHub organization) maintains it in zalando/skipper, which has 3,331 GitHub stars. The repository holds 5 skills in this directory. The repository was last updated on October 6, 2026.

Source: zalando/skipper on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.