verification-before-completion

verification-before-completion is a skill for Claude Code from moberghr/mtk-agent-toolkit. It costs 27 tokens per session (4,618 once invoked), scanned B, original, MIT.

A completion-checking practice that requires fresh command output before saying a task is finished.

In plain words
What is it for?
Use it to verify fixes, batches, builds, and other work before reporting them as complete.
Why use it?
It prevents claims based only on assumptions, remembered results, or files that were not actually tested after the latest change.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: reads .claude/ paths; mentions subagents; mentions Codex.

Not installable on its own: it runs a file from its repository that does not travel with it. Clone the repository, or install whatever ships that file. The line is bash scripts/validate-toolkit.sh --task-scoped <comma-separated paths>.

Part of the mtk plugin — 45 skills, 6 agents, 7 hooks, 1 MCP server shipped together

Install

Getting it into your agent

This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.

Claude Code
/plugin marketplace add moberghr/mtk-agent-toolkit
Claude Code
/plugin install mtk

Made for: Claude Code.

Or install mtk, the plugin that ships this one along with the rest of its 45 skills, 6 agents, 7 hooks, 1 MCP server.

Wrote 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.

agentmods badge for verification-before-completion

README.md
[![agentmods](https://agentmods.dev/badge/skills/moberghr/mtk-agent-toolkit/verification-before-completion.svg)](https://agentmods.dev/skills/moberghr/mtk-agent-toolkit/verification-before-completion)
Your own site
<a href="https://agentmods.dev/skills/moberghr/mtk-agent-toolkit/verification-before-completion"><img src="https://agentmods.dev/badge/skills/moberghr/mtk-agent-toolkit/verification-before-completion.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,618 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00027 $0.04618
Opus 5 $0.00014 $0.02309
Sonnet 5 $0.00005 $0.00924
Haiku 4.5 $0.00003 $0.00462

Measured 6d ago against content hash b38669b156ea, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade B, and why

verification-before-completion scanned grade B with 2 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 6d 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.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

cat .claude/tech-stack 2>/dev/null || echo "(not set)"

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

| SC2 | verified | `curl :5080/health → 200, body {"status":"ok"}` |
.claude/skills/verification-before-completion/SKILL.md · 270 lines

How it starts

The opening of the file, as written. The whole thing — 270 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Verification Before Completion

Active Stack

echo "--- Tech Stack ---"
cat .claude/tech-stack 2>/dev/null || echo "(not set)"

Overview

No completion claim is valid without fresh evidence from an actual command execution. "Should work," "probably fixed," and "looks correct" are not verification. Run the command, read the output, check the exit code, then state the result with evidence.

Verification contract. Every success criterion carries an evidence_channel (the surface where the observable result is captured) and an observable (a binary pass/fail statement declared before execution). Verification must go criterion-by-criterion — trust the list over memory. For behavior-shaped changes, tests alone never prove done: the evidence_channel must be a real execution surface (smoke-boot, http-probe, db-state-diff, cli-stdout, or browser), not a build artifact.

Re-arm rule. Any edit that lands after the most recent verification resets every criterion's status to re-armed. A completion claim is rejected while any criterion is re-armed. Re-verification must run after the edit, cite the observable result per criterion, and set each criterion to verified before the claim is accepted.

Frozen Criteria & Tamper Check

The success_criteria[] definitions (id, observable, evidence_channel) are frozen at Phase 2.5 approval. They are the goalposts; the run is not allowed to move them. The criteria are read-only ground truth during implementation — the same invariant F15 (Frozen-Replay / Non-Varying Evidence) names: editing what measures you to move the number defeats the gate.

Before accepting any completion claim, run the tamper check: confirm the frozen criteria block has not changed since approval. The spec sidecar is committed at Phase 2.5, so the cheapest check is a diff of the criteria block against the approved version:

# Tamper check: did success_criteria change since the spec was approved?
git diff --no-color <approval-ref>..HEAD -- docs/specs/<date>-<slug>.json \
  | grep -E '"(id|observable|evidence_channel)"' || echo "criteria intact"

Read the full file on GitHub · 270 lines

Changes

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.

  1. 6d ago First seen · 270 lines · 27 tokens per session scan B b38669b156ea

Subscribe to this mod's changes

verification-before-completion is a skill published in the GitHub repository moberghr/mtk-agent-toolkit (7 stars, last pushed yesterday), licensed MIT. It adds 27 tokens to every session and 4,618 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it B with 2 findings (reads agent configuration directories, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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