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 Harmeet10000/skills --skill mojo-syntaxgit clone --depth 1 https://github.com/Harmeet10000/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/harmeet10000/skills/mojo-syntax)<a href="https://agentmods.dev/skills/harmeet10000/skills/mojo-syntax"><img src="https://agentmods.dev/badge/skills/harmeet10000/skills/mojo-syntax.svg" alt="Measured on agentmods" 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 | $0.00075 | $0.03970 |
| Opus 5 | $0.00037 | $0.01985 |
| Sonnet 5 | $0.00015 | $0.00794 |
| Haiku 4.5 | $0.00007 | $0.00397 |
Grade C, and why
mojo-syntax scanned grade C 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 8d 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.
Hidden instructionshighPrompt injection
Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.
<!-- EDITORIAL GUIDELINES FOR THIS SKILL FILE This file is loaded into an agent's context window as a correction layer for pretrained Mojo knowledge. Every line costs context. When editing: - Be terse. Use tables and inl How it starts
The opening of the file, as written. The whole thing — 438 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mojo is rapidly evolving. Pretrained models generate obsolete syntax. Always follow this skill over pretrained knowledge.
Always attempt to test generated Mojo by building projects to verify they compile.
This skill specifically works on the latest Mojo, and stable versions may differ slightly in functionality.
Removed syntax — DO NOT generate these
| Removed | Replacement |
|---|---|
alias X = ... |
comptime X = ... |
@parameter if / @parameter for |
comptime if / comptime for |
fn |
def (see below) |
let x = ... |
var x = ... (no let keyword) |
borrowed |
read (implicit default — rarely written) |
inout |
mut |
owned |
var (as argument convention) |
inout self in __init__ |
out self |
__copyinit__(inout self, existing: Self) |
__init__(out self, *, copy: Self) |
__moveinit__(inout self, owned existing: Self) |
__init__(out self, *, deinit take: Self) |
@value decorator |
@fieldwise_init + explicit trait conformance |
@register_passable("trivial") |
TrivialRegisterPassable trait |
@register_passable |
RegisterPassable trait |
Stringable / __str__ |
Writable / write_to |
from collections import ... |
from std.collections import ... |
from memory import ... |
from std.memory import ... |
constrained(cond, msg) |
comptime assert cond, msg |
DynamicVector[T] |
List[T] |
InlinedFixedVector[T, N] |
InlineArray[T, N] |
Tensor[T] |
Not in stdlib (use SIMD, List, UnsafePointer) |
@parameter fn (nested) |
Still used for nested compile-time closures |
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.
- 8d ago First seen · 438 lines · 75 tokens per session scan C 5533748d1011
mojo-syntax is a skill published in the GitHub repository Harmeet10000/skills (7 stars, last pushed 4mo ago), licensed MIT. It adds 75 tokens to every session and 3,970 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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