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.
npx skills add G1Joshi/Agent-Skills --skill cgit clone --depth 1 https://github.com/G1Joshi/Agent-SkillsWrote 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.
[](https://agentmods.dev/skills/g1joshi/agent-skills/c)<a href="https://agentmods.dev/skills/g1joshi/agent-skills/c"><img src="https://agentmods.dev/badge/skills/g1joshi/agent-skills/c/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.
<a href="https://agentmods.dev/skills/g1joshi/agent-skills/c"><img src="https://agentmods.dev/badge/skills/g1joshi/agent-skills/c.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00038 | $0.01049 |
| Opus 5.5 | $0.00015 | $0.00420 |
| Sonnet 5.5 | $0.00008 | $0.00210 |
| Haiku 4.5 | $0.00004 | $0.00105 |
Grade A, and why
c scanned grade A with 0 findings 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 22d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 148 lines — stays where its author put it; the contents beside it link to each section on GitHub.
C
The foundational language for modern computing, operating systems, and embedded systems.
When to Use
- Operating System Kernels & Drivers: Developing the Linux kernel, device drivers, and low-level firmware.
- High-Performance Embedded Systems: Microcontroller programming (ARM Cortex, RISC-V) with strict real-time memory constraints.
- Foundational Infrastructure & Databases: Powering core engines like SQLite, Redis, Nginx, and Python runtimes.
- Hardware-Accelerated Audio / Video Codecs: Building zero-overhead media codecs and DSP signal processing routines.
Quick Start
#include <stdio.h>
int main() {
printf("Hello, World!\n");
return 0;
}
Core Concepts
Explicit Memory Management & Pointer Arithmetic
Direct manipulation of memory addresses, stack allocation, and heap lifetimes:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct {
size_t length;
char *data;
} StringBuffer;
StringBuffer* buffer_create(const char *initial_str) {
StringBuffer *buf = malloc(sizeof(StringBuffer));
if (!buf) return NULL;
buf->length = strlen(initial_str);
buf->data = malloc(buf->length + 1);
if (!buf->data) {
free(buf);
return NULL;
}
memcpy(buf->data, initial_str, buf->length + 1);
return buf;
}
void buffer_free(StringBuffer *buf) {
if (buf) {
free(buf->data);
free(buf);
}
}
Modern C Standards (C23 / C17) Features
C23 introduces standardized bool, nullptr, and auto type inference:
// Modern C23 syntax
#include <stdbool.h>
int main(void) {
bool is_active = true;
void *ptr = nullptr; // C23 standardized nullptr
return is_active ? 0 : 1;
}
Memory Sanitizers (ASan & UBSan)
Instruments binary builds to detect buffer overflows, use-after-free, and undefined behavior at runtime:
# Compile with AddressSanitizer and UndefinedBehaviorSanitizer
gcc -std=c17 -Wall -Wextra -Werror -fsanitize=address,undefined -g -O1 main.c -o app
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.
- 22d ago Changed f17eab38e4b8
- 26d ago Changed · +77 lines · +15 tokens per session 2642b4d479af
- 1mo ago First seen · 71 lines · 23 tokens per session scan A 2f3f9ddf7329
c is a skill published in the GitHub repository G1Joshi/Agent-Skills (15 stars, last pushed 22d ago), licensed MIT. It adds 38 tokens to every session and 1,049 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
Other skills, from other repositories
esp32-arduino-embedded-c
Guidance for production-grade ESP32 Arduino and Embedded C/C++ development. Use when building firmware for ESP32, ESP32-S3, or ESP32-C3 microcontrollers, optimizing FreeRTOS tasks, managing SRAM/PSRAM, writing ISR-safe code, or handling dual-core concurrency and hardware peripherals.
raspberry-pi-rust-embedded
Production-grade embedded Rust guidelines for Raspberry Pi (bare-metal nostd and Linux embedded std/rppal/embedded-hal). Use when developing low-latency hardware control apps, embedded Rust drivers, Linux GPIO/SPI/I2C/UART software, real-time interrupt handlers, and memory-safe hardware abstractions.
context-engineering
Optimizes agent context setup. Use when starting a new session, when agent output quality degrades, when switching between tasks, or when you need to configure rules files and context for a project.
doubt-driven-development
Subjects every non-trivial decision to a fresh-context adversarial review before it stands. Use when you want every assumption cross-examined before proceeding, when stress-testing a plan for hidden failure modes, when correctness matters more than speed, when working in unfamiliar code, when stakes are high…
observability-and-instrumentation
Instruments code so production behavior is visible and diagnosable. Use when adding logging, metrics, tracing, or alerting. Use when shipping any feature that runs in production and you need evidence it works. Use when production issues are reported but you can't tell what happened from the available data.
performance-optimization
Optimizes application performance across frontend, backend, queries, and databases. Use when performance requirements exist, when you suspect performance regressions, when Core Web Vitals or load times need improvement, when N+1 query patterns need fixing, or when profiling reveals bottlenecks.