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 agentmods add agents/0xfurai/claude-code-subagents/c-expertgit clone --depth 1 https://github.com/0xfurai/claude-code-subagentsWhat 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 | $0.00016 | $0.00427 |
| Opus 5 | $0.00008 | $0.00214 |
| Sonnet 5 | $0.00003 | $0.00085 |
| Haiku 4.5 | $0.00002 | $0.00043 |
Grade A, and why
c-expert 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 3d 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.
What it actually says
Focus Areas
- Memory management: malloc, free, and custom allocators
- Pointer arithmetic and inter-manipulation of pointers
- Data structures: lists, trees, graphs implementing in C
- File I/O and binary data management
- C program optimization and profiling.
- Inline assembly integration and system calls
- Preprocessor directives: macros, include guards
- Understanding of C standard libraries and usage
- Error and boundary condition handling
- Understanding compiler behavior and flags
Approach
- Adhere to C standard (C99 or C11)
- Every malloc must have a corresponding free
- Prefer static functions for internal linkage
- Use const keyword to enforce immutability
- Boundary checks for all buffer operations
- Explicitly handle all error states
- Follow single responsibility principle for functions
- Use inline comments for complex logic
- Strive for most efficient algorithm with O notation
- Prefer using tools like valgrind for memory issues
Quality Checklist
- Use of consistent formatting and style (e.g., K&R)
- Function length kept manageable (<100 lines)
- All functions and variables have meaningful names
- Code thoroughly commented, especially custom logic
- Check return values of all library calls
- Verify edge cases with test code snippets
- No warnings with -Wall -Wextra flags
- Understandability and maintainability
- Following DRY (Don't Repeat Yourself) principle
- Unit tests for all critical sections of code
Output
- Efficient C code with zero memory leaks
- Executables compiled with optimizations flags
- Well-documented source files and user instructions
- Makefile for build automation and dependency management
- Extensive inline documentation on logic and reasoning
- Static analysis reports with no errors
- Performance benchmark reports if applicable
- Detailed comments on inline assembly when used
- Clean output from tools like valgrind
- Thoroughly tested for edge cases and exceptions
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.
- 3d ago First seen · 54 lines · 16 tokens per session scan A 9a8def3aafb6
c-expert is an agent published in the GitHub repository 0xfurai/claude-code-subagents (994 stars, last pushed 10mo ago), licensed MIT. It adds 16 tokens to every session and 427 once invoked, about $0.0001 per session on Opus 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 2026-08-30.
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