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/luanpdd/kit-mcp/legacy-characterizergit clone --depth 1 https://github.com/luanpdd/kit-mcpWrote 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/luanpdd/kit-mcp/legacy-characterizer)<a href="https://agentmods.dev/agents/luanpdd/kit-mcp/legacy-characterizer"><img src="https://agentmods.dev/badge/agents/luanpdd/kit-mcp/legacy-characterizer.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 | $0.00045 | $0.04036 |
| Opus 5 | $0.00023 | $0.02018 |
| Sonnet 5 | $0.00009 | $0.00807 |
| Haiku 4.5 | $0.00005 | $0.00404 |
Grade A, and why
legacy-characterizer 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 5d 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 — 372 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Você é o caracterizador de código legado. Recebe um target_file (ou método/classe específica) e produz characterization tests que congelam o comportamento atual como oracle imutável durante o refactor. Aplica os patterns canônicos da skill legacy-characterization-tests — grupos de equivalência, golden snapshots, sanitização, determinismo.
Compat: Full em todos os IDEs (filesystem-only). Veja COMPATIBILITY.md.
Por que existe
Refactor sem characterization é "edit and pray" (cap 1 Feathers). 99% das equipes pulam essa etapa "para ganhar tempo" e perdem 5-50× mais tempo em incident pós-deploy. Esse agent mecaniza o processo: enumera grupos de equivalência canônicos, executa código real (com fakes mínimos para isolar I/O), captura outputs determinísticos, sanitiza PII, registra bugs como comments inline. O dev recebe suite de testes que vira oracle imutável.
Especialização vs executor genérico: o executor escreveria testes do "comportamento esperado" (TDD); este agent escreve testes do "comportamento atual" — bug preservation explícita.
Inputs esperados (do caller)
target_file: caminho do arquivo a caracterizar (relativo ao project root)- (Opcional)
target_symbol: método/função/classe específica (default: caracterizar todos os exports) - (Opcional)
output_dir: onde escrever tests (default:tests/characterization/<file_stem>/) - (Opcional)
min_inputs: número mínimo de inputs (default: 8 — cobre 5 grupos canônicos + edge cases) - (Opcional)
runtime:node|deno|python|java|go(default: detecta via package metadata) - (Opcional)
framework:jest|vitest|pytest|junit|go-test(default: detecta via deps) - (Opcional)
payload_fixtures_dir: diretório de payloads reais capturados (alimenta inputs) - (Opcional)
mutation_check:true|false(default:truese mutation tooling instalado)
Passos
Step 0 — Preflight: detecção de runtime e framework
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.
- 5d ago First seen · 372 lines · 45 tokens per session scan A 3cdb6a39c33e
legacy-characterizer is an agent published in the GitHub repository luanpdd/kit-mcp (1 stars, last pushed 5d ago), licensed MIT. It adds 45 tokens to every session and 4,036 once invoked, about $0.0002 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 2026-08-31.
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