Agent skill

Add Function Body

Add a function body definition to an ONNX operator, defining how it decomposes into simpler ops.

Apache-2.0Auto-check passedAI & LLM Engineering

Install Add Function Body

skills CLI

$ npx skills add onnx/onnx --skill add-function-body -a claude-code

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

GitHub CLI

$ gh skill install onnx/onnx add-function-body --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/onnx/onnx.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/skills/add-function-body .claude/skills/add-function-body && 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/

Paste into Claude Code

Install the "add-function-body" agent skill from https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body into .claude/skills/add-function-body/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-function-body", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add onnx/onnx --skill add-function-body -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install onnx/onnx add-function-body --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/onnx/onnx.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.agents/skills/add-function-body .agents/skills/add-function-body && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "add-function-body" agent skill from https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body into .agents/skills/add-function-body/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-function-body", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add onnx/onnx --skill add-function-body -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install onnx/onnx add-function-body --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/onnx/onnx.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.agents/skills/add-function-body .cursor/skills/add-function-body && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "add-function-body" agent skill from https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body into .cursor/skills/add-function-body/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-function-body", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/onnx/onnx.git --path .agents/skills/add-function-body

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add onnx/onnx --skill add-function-body -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install onnx/onnx add-function-body --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/onnx/onnx.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.agents/skills/add-function-body .gemini/skills/add-function-body && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "add-function-body" agent skill from https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body into .gemini/skills/add-function-body/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-function-body", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install onnx/onnx add-function-body

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add onnx/onnx --skill add-function-body -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/onnx/onnx.git skills-src && mkdir -p .github/skills && cp -r skills-src/.agents/skills/add-function-body .github/skills/add-function-body && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "add-function-body" agent skill from https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body into .github/skills/add-function-body/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-function-body", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add onnx/onnx --skill add-function-body -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install onnx/onnx add-function-body --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/onnx/onnx.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.agents/skills/add-function-body .opencode/skills/add-function-body && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "add-function-body" agent skill from https://github.com/onnx/onnx/tree/main/.agents/skills/add-function-body into .opencode/skills/add-function-body/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "add-function-body", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: add-function-body
GitHub stars: 22k
Token cost: ~1.1k tokens
SKILL.md length: 231 words
Files: 1
Skills in repo: 4
Repo updated: Oct 7, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Add a function body definition to an ONNX operator, defining how it decomposes into simpler ops.

Asked to make an op decomposable
SKILL.md covers File Locations, Method 1: Simple String-Based…, Method 2: Context-Dependent… and FunctionBuilder API, plus 5 more sections
Calls python
Add a FunctionBody

What it does

Add Function Body is an agent skill from onnx/onnx. Add a function body definition to an ONNX operator, defining how it decomposes into simpler ops. Use when asked to make an op decomposable, add a FunctionBody, implement SetContextDependentFunctionBodyBuilder, or express an op in terms of other ONNX operators.

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in AI & LLM Engineering, covering Deep learning. It works with ONNX. The repository describes itself as: Open standard for machine learning interoperability. The licence is Apache-2.0.

When your agent uses it

Asked to make an op decomposable
Add a FunctionBody
Implement SetContextDependentFunctionBodyBuilder
Express an op in terms of other ONNX operators

Example prompts

“/add-function-body”

Requirements

Python 3

What it can do on your machine

Read from SKILL.md and the folder at commit ab429ea. 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
Shell commands in SKILL.md call:
- python
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.

Context cost

Add Function Body loads about 1.1k tokens when it runs. Until then it costs about 70 tokens; SKILL.md has 231 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~70
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

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 onnx/onnx at commit ab429ea, republished under its Apache-2.0 licence (© onnx). 231 words, ~1,052 tokens.

Download SKILL.mdSave it as .claude/skills/add-function-body/SKILL.md (or your agent's skills folder).

name: add-function-body
description: Add a function body definition to an ONNX operator, defining how it decomposes into simpler ops. Use when asked to make an op decomposable, add a FunctionBody, implement SetContextDependentFunctionBodyBuilder, or express an op in terms of other ONNX operators.

Follow the full guide in docs/AddFunctionBody.md.

File Locations

Component	File
Function body definition	`onnx/defs/<domain>/defs.cc` (inline with schema)
FunctionBuilder utilities	`onnx/defs/function.h`
Function tests	`tests/cpp/function_get_test.cc`, `tests/cpp/function_verify_test.cc`

Method 1: Simple String-Based Function Body

cpp

ONNX_OPERATOR_SET_SCHEMA(
    LessOrEqual, 16,
    OpSchema()
        // ... inputs, outputs, type constraints ...
        .TypeAndShapeInferenceFunction(inferenceFunction)
        .FunctionBody(R"ONNX(
        {
            O1 = Less (A, B)
            O2 = Equal (A, B)
            C = Or (O1, O2)
        }
        )ONNX"));

With explicit opset version:

cpp

        .FunctionBody(R"ONNX(...)ONNX", 18)  // Valid from opset 18

Referencing attributes with @attr_name:

cpp

        .FunctionBody(R"ONNX(
          {
            Alpha = Constant <value_float: float = @alpha>()
            AlphaCast = CastLike (Alpha, X)
            ...
          }
        )ONNX")

Method 2: Context-Dependent Function Body

For ops whose decomposition varies based on attributes or optional inputs:

cpp

static bool BuildFunctionBodyMyOp(
    const FunctionBodyBuildContext& ctx,
    const OpSchema& schema,
    FunctionProto& functionProto) {
  FunctionBuilder builder(functionProto);
  // Build graph based on ctx.hasInput(), ctx.getAttribute(), etc.
  builder.Add("output = SomeOp (input)");
  schema.BuildFunction(functionProto);
  return true;
}

// Register:
    .SetContextDependentFunctionBodyBuilder(BuildFunctionBodyMyOp)

FunctionBuilder API

cpp

FunctionBuilder builder(functionProto);
builder.Add("Y = Relu (X)");                          // Add node
builder.Const("alpha", std::vector<float>{0.01f});    // Constant tensor
builder.Const1D("axes", int64_t(1));                  // 1-D constant
builder.Add(R"(                                       // Multi-line
    X_Sub = Sub (X, X_Max)
    X_Exp = Exp (X_Sub)
)");
builder.AddOpset("", 18);                             // Opset dependency
schema.BuildFunction(functionProto);                  // Finalize
return true;

Multiple Opset Versions

cpp

    .SetContextDependentFunctionBodyBuilder(builderForOpset13)
    .SetContextDependentFunctionBodyBuilder(builderForOpset18, 18)

ONNX Function Body Syntax

Function body strings use the ONNX text format ("onnxtxt"). See the onnxtxt skill for the full syntax cheat sheet, attribute references (@attr_name), Constant <value = ...> forms, CastLike vs Cast, body-subgraph idioms, and parser tests. Quick reminders specific to function bodies:

Variable names are local intermediates; input/output names must match the schema's declared names.
Reference enclosing-op attributes with @attr_name — and only those declared in .Attr(...) calls.
Use CastLike (not Cast) when the target type depends on another input.

Code Style: Prefer Named Functions

Define context-dependent function body builders as separate named functions rather than inline lambdas within ONNX_OPERATOR_SET_SCHEMA. The macro expansion makes setting breakpoints on inline lambdas unreliable in debuggers.

Simple string-based .FunctionBody(R"ONNX(...)ONNX") definitions don't have this issue.

After Making Changes

bash

python onnx/defs/gen_doc.py
lintrunner -a --output oneline

Common Mistakes

Forgetting schema.BuildFunction(functionProto) at end of context-dependent builders
Forgetting to return true from the builder function
Variable names conflicting with input/output names
Using Cast instead of CastLike for dynamic type matching
Function body not producing all declared outputs
Using @attr_name for an attribute not declared in .Attr() calls

Files

Just SKILL.md in .agents/skills/add-function-body of onnx/onnx.

Open the folder on GitHubat commit ab429ea

Compare with similar skills

Add Function Body 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.

Add Function Body compared with similar skills
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Segment Anything Model GuideOrchestra-Research/AI-Research-SKILLs	13k	9 repos	~3.3k	Automated safety check: Pass	MIT	3 mo ago
Technology Selectiondotnet/skills	5.6k	2 repos	~2.1k	Automated safety check: Pass	MIT	today
Quark Torch Quant Perfamd/Quark	181	—	~3k	Automated safety check: Pass	MIT	9 days ago
Domain MLmajiayu000/claude-skill-registry	666	1 repos	~1.2k	Automated safety check: Pass	MIT	today
Embedded AI Deploymentmatlab/agent-skills-playground	181	1 repos	~3.4k	Automated safety check: Pass	Custom licence	26 days ago

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Questions about Add Function Body

What does Add Function Body do?

Add a function body definition to an ONNX operator, defining how it decomposes into simpler ops. Add Function Body is an agent skill from onnx/onnx. Add a function body definition to an ONNX operator, defining how it decomposes into simpler ops.

When should I use Add Function Body?

Add Function Body fits situations like: asked to make an op decomposable; add a FunctionBody; implement SetContextDependentFunctionBodyBuilder; express an op in terms of other ONNX operators.

How do I install Add Function Body in Claude Code?

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

How do I install Add Function Body in Codex?

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

Can I use Add Function Body 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 onnx/onnx --skill add-function-body -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/add-function-body, .gemini/skills/add-function-body, .github/skills/add-function-body and .opencode/skills/add-function-body in your project.

What does Add Function Body need to run?

Going by SKILL.md and its folder, Add Function Body needs the command-line tools its instructions call (python). Our summary lists: Python 3.

Does Add Function Body 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 Add Function Body 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 Add Function Body use?

Add Function Body is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Add Function Body use?

About 1.1k tokens (SKILL.md is roughly 4.2k 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 Add Function Body?

Skills that share tags, products or a category with Add Function Body: Segment Anything Model Guide (Orchestra-Research/AI-Research-SKILLs, 13k stars), Technology Selection (dotnet/skills, 5.6k stars), Quark Torch Quant Perf (amd/Quark, 181 stars) and Domain ML (majiayu000/claude-skill-registry, 666 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Add Function Body?

onnx (a GitHub organization) maintains it in onnx/onnx, which has 21,562 GitHub stars. The repository holds 4 skills in this directory. The repository was last updated on October 7, 2026.

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

Add Function Body

Install Add Function Body

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

File Locations

Method 1: Simple String-Based Function Body

Method 2: Context-Dependent Function Body

FunctionBuilder API

Multiple Opset Versions

ONNX Function Body Syntax

Code Style: Prefer Named Functions

After Making Changes

Common Mistakes

Files

Compare with similar skills

Similar skills

Segment Anything Model Guide

Technology Selection

Quark Torch Quant Perf

Domain ML

Embedded AI Deployment

Model Builder

More from onnx/onnx

Add Op

Add Shape Inference

Onnxtxt

Questions about Add Function Body

Install Add Function Body

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

File Locations

Method 1: Simple String-Based Function Body

Method 2: Context-Dependent Function Body

FunctionBuilder API

Multiple Opset Versions

ONNX Function Body Syntax

Code Style: Prefer Named Functions

After Making Changes

Common Mistakes

Files

Compare with similar skills

Similar skills

More from onnx/onnx

Related

Questions about Add Function Body