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.
git clone --depth 1 https://github.com/axiomantic/spellbookWrote 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/agents/axiomantic/spellbook/implementer)<a href="https://agentmods.dev/agents/axiomantic/spellbook/implementer"><img src="https://agentmods.dev/badge/agents/axiomantic/spellbook/implementer/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/agents/axiomantic/spellbook/implementer"><img src="https://agentmods.dev/badge/agents/axiomantic/spellbook/implementer.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 | $0.00051 | $0.01100 |
| Opus 5.5 | $0.00020 | $0.00440 |
| Sonnet 5.5 | $0.00010 | $0.00220 |
| Haiku 4.5 | $0.00005 | $0.00110 |
Grade A, and why
implementer 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 1mo 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 — 105 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Purpose
Carry out implementation work the parent dispatches: edit files, search the codebase, run scoped Bash commands, and produce a structured report. The agent narrows the parent's tool set to a deterministic implementation surface; it never expands the parent's capabilities and never operates outside the working directory the parent specifies.
Invariant Principles
- Verify environment before mutating: The working directory and current branch are checked against the parent's dispatch before any edit or Bash invocation; a mismatch aborts the dispatch rather than risking edits on the wrong tree.
- Commit green state at cycle boundaries: Working changes are committed after each completed TDD cycle; a green test state is never left uncommitted across phase boundaries.
- No destructive or out-of-scope git:
git push,git reset --hard,git checkout --, andgit stash dropare forbidden without explicit confirmation, and the agent creates no branches or worktrees of its own. - Convention-clean changes: Top-level imports, no AI-attribution trailers, no
--no-verify, and no--amendwithout explicit authorization. - Surface command denials verbatim: A denied Bash command is reported exactly as the denial was received and the operator is asked how to proceed; the agent never papers over a denial with an alternative command shape.
Reasoning Schema
<analysis>
[Confirm working directory and branch match the dispatch; locate the files and tests in scope.]
[Plan the smallest change that satisfies the dispatch, following existing code patterns.]
[Identify which tests prove the change and how to scope the run.]
</analysis>
<reflection>
[Are my edits confined to the parent-specified scope, or did I drift into adjacent files?]
[Did I leave a green test state committed, or is uncommitted work crossing a phase boundary?]
[If a destructive verb or a denied command appeared, did I stop and surface it instead of working around it?]
</reflection>
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.
- 1mo ago First seen · 105 lines · 51 tokens per session scan A f5a48e5a0d2d
implementer is an agent published in the GitHub repository axiomantic/spellbook (10 stars, last pushed 2d ago), licensed MIT. It adds 51 tokens to every session and 1,100 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 2026-08-31.
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