develop_extension

develop_extension is a skill for Claude Code, Codex from OpenBB-finance/OpenBB. It costs 53 tokens per session (5,062 once invoked), scanned A, original, no licence file.

A complete guide for creating an OpenBB Platform extension from an empty project. An extension adds new functionality to the OpenBB finance platform.

In plain words
What is it for?
Use it when building and checking a new OpenBB Platform extension.
Why use it?
It gives you an ordered path through scaffolding, implementation, installation, and verification.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit Use it when building and checking a new OpenBB Platform extension.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/openbb-finance/openbb/develop_extension
Install

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.

Any agent
npx skills add OpenBB-finance/OpenBB --skill develop_extension
Clone the repo
git clone --depth 1 https://github.com/OpenBB-finance/OpenBB

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for develop_extension

README.md
[![agentmods](https://agentmods.dev/badge/skills/openbb-finance/openbb/develop_extension/github.svg)](https://agentmods.dev/skills/openbb-finance/openbb/develop_extension)
Your own site
<a href="https://agentmods.dev/skills/openbb-finance/openbb/develop_extension"><img src="https://agentmods.dev/badge/skills/openbb-finance/openbb/develop_extension/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for develop_extension

Your own site · 80×15
<a href="https://agentmods.dev/skills/openbb-finance/openbb/develop_extension"><img src="https://agentmods.dev/badge/skills/openbb-finance/openbb/develop_extension.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,062 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe. ✓ AI security review Fable 5.1 · 6 Sept 2026 📄 Read the review Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 3 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high Prompt Injection · line 1
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
  • medium Data Exfiltration · line 159
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
  • medium Data Exfiltration · line 205
    Data is being sent to an external URL. This could be legitimate telemetry or data exfiltration. Manual review is recommended.
    Fix: Verify the destination URL is trusted and necessary. Remove or replace with documented APIs. Ensure no secrets, tokens, or PII are transmitted.
How audits are shown
Origin unknown No closer match found in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00053 $0.05062
Opus 5.5 $0.00021 $0.02025
Sonnet 5.5 $0.00011 $0.01012
Haiku 4.5 $0.00005 $0.00506

Measured 17d ago against content hash 95270d0c798f, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

develop_extension scanned grade A with 1 finding 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 17d ago.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

All `requests.get`/`requests.post` keyword arguments are passed through.
openbb_platform/extensions/mcp_server/openbb_mcp_server/skills/develop_extension/SKILL.md · 658 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

Read it on GitHub

Changes

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.

  1. 17d ago Changed · +40 lines 95270d0c798f
  2. 1mo ago First seen · 618 lines · 53 tokens per session scan A 8b7fa8d4449b

Subscribe to this mod's changes

develop_extension is a skill published in the GitHub repository OpenBB-finance/OpenBB (73,659 stars, last pushed 17d ago), with no licence file. It adds 53 tokens to every session and 5,062 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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