credentials

Guidance for checking whether required API keys or other credentials exist and asking the user to add missing ones safely. Credentials are secrets used to access services.

In plain words
What is it for?
It helps verify credential presence without printing keys, check environment files, and follow a safe process when a required credential is missing.
Why use it?
It reduces the risk of exposing secret values while checking configuration or preparing a skill that needs authentication.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/google-deepmind/science-skills/credentials
Any agent
npx skills add google-deepmind/science-skills --skill credentials
Clone the repo
git clone --depth 1 https://github.com/google-deepmind/science-skills

Made for: Claude Code, Codex.

Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 971 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin original 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 $0.00029 $0.00971
Opus 5 $0.00015 $0.00485
Sonnet 5 $0.00006 $0.00194
Haiku 4.5 $0.00003 $0.00097

Measured yesterday against content hash 82f252acbf13, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

credentials scanned grade B 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 yesterday.

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.

Unrestricted tool accessmediumExcessive agency

A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.

before attempting to run any scripts or tools. Do not conclude the turn by
skills/credentials/SKILL.md · 96 lines

How it starts

The opening of the file, as written. The whole thing — 96 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Safe Credentials Protocol

Many skills require API keys or other credentials to function or to access higher rate limits. This skill defines the standard safe credentials protocol for verifying and prompting for these credentials without leaking sensitive keys into the agent context or the conversation history.

Safe Verification (No Leaks)

As soon as a skill that requires a credential or API key looks relevant to the user's request, you MUST immediately verify if the credential is present in the .env file (typically located in your home directory ~/.env or the project root) — before doing any other work for that skill.

CRITICAL: You must verify the presence of the credential without printing its value to the terminal or reading it into your context.

How to verify:

Use grep in quiet and suppress-errors mode (-sq) to check if the variable is defined in ~/.env. The -s flag ensures the command works cleanly even if ~/.env does not exist yet.

grep -sq "^CREDENTIAL_NAME=" ~/.env

Replace CREDENTIAL_NAME with the actual credential name required by the calling skill (e.g., ALPHAGENOME_API_KEY or USER_EMAIL).

  • If the command succeeds (exit code 0), the credential is present. You can proceed.
  • If the command fails (any non-zero exit code — whether the credential is missing or the .env file does not exist yet), the credential is missing. You MUST IMMEDIATELY stop and prompt the user to add it using the instructions in Prompting the User to Add Credentials before attempting to run any scripts or tools. Do not conclude the turn by simply stating that the key is missing.

[!CRITICAL] If verification fails (any non-zero exit code), you MUST NOT attempt to execute any tools or scripts from the calling skill, nor should you conclude the turn by simply reporting the missing key. You MUST IMMEDIATELY generate the appropriate terminal command from the templates below and prompt the user to run it. The template command will create the .env file if it does not already exist.

Read the full file on GitHub · 96 lines

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. yesterday First seen · 96 lines · 29 tokens per session scan B 82f252acbf13

Subscribe to this mod's changes

credentials is a skill published in the GitHub repository google-deepmind/science-skills (2,794 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 29 tokens to every session and 971 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 1 finding (unrestricted tool access). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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