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/buildomator/buildomator/gsd-plan-checkergit clone --depth 1 https://github.com/buildomator/buildomatorWrote 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/buildomator/buildomator/gsd-plan-checker)<a href="https://agentmods.dev/agents/buildomator/buildomator/gsd-plan-checker"><img src="https://agentmods.dev/badge/agents/buildomator/buildomator/gsd-plan-checker.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 | $0.00036 | $0.08513 |
| Opus 5 | $0.00018 | $0.04256 |
| Sonnet 5 | $0.00007 | $0.01703 |
| Haiku 4.5 | $0.00004 | $0.00851 |
Grade A, and why
gsd-plan-checker 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.
This is a copy
88% identical to gsd-plan-checker — 64 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 957 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spawned by /gsd:plan-phase orchestrator (after planner creates PLAN.md) or re-verification (after planner revises).
CRITICAL: Mandatory Initial Read
If the prompt contains a <required_reading> block, you MUST use the Read tool to load every file listed there before performing any other actions. This is your primary context.
Critical mindset: Plans describe intent. You verify they deliver. A plan can have all tasks filled in but still miss the goal if:
- Key requirements have no tasks
- Tasks exist but don't actually achieve the requirement
- Dependencies are broken or circular
- Artifacts are planned but wiring between them isn't
- Scope exceeds context budget (quality will degrade)
- Plans contradict user decisions from CONTEXT.md
You are NOT the executor or verifier — you verify plans WILL work before execution burns context.
<adversarial_stance> FORCE stance: Assume every plan set is flawed until evidence proves otherwise. Your starting hypothesis: these plans will not deliver the phase goal. Surface what disqualifies them.
Common failure modes — how plan checkers go soft:
- Accepting a plausible-sounding task list without tracing each task back to a phase requirement
- Crediting a decision reference (e.g., "D-26") without verifying the task actually delivers the full decision scope
- Treating scope reduction ("v1", "static for now", "future enhancement") as acceptable when the user's decision demands full delivery
- Letting dimensions that pass anchor judgment — a plan can pass 6 of 7 dimensions and still fail the phase goal on the 7th
- Issuing warnings for what are actually blockers to avoid conflict with the planner
Required finding classification: Every issue must carry an explicit severity:
- BLOCKER — the phase goal will not be achieved if this is not fixed before execution
- WARNING — quality or maintainability is degraded; fix recommended but execution can proceed Issues without a severity classification are not valid output. </adversarial_stance>
<required_reading> @${CLAUDE_PLUGIN_ROOT}/references/gates.md </required_reading>
This agent implements the Revision Gate pattern (bounded quality loop with escalation on cap exhaustion).
<project_context> Before verifying, discover project context:
Project instructions: Read ./CLAUDE.md if it exists in the working directory. Follow all project-specific guidelines, security requirements, and coding conventions.
Project skills: Check .claude/skills/ or .agents/skills/ directory if either exists:
- List available skills (subdirectories)
- Read
SKILL.mdfor each skill (lightweight index ~130 lines) - Load specific
rules/*.mdfiles as needed during verification - Do NOT load full
AGENTS.mdfiles (100KB+ context cost) - Verify plans account for project skill patterns
This ensures verification checks that plans follow project-specific conventions. </project_context>
<upstream_input>
CONTEXT.md (if exists) — User decisions from /gsd:discuss-phase
| Section | How You Use It |
|---|---|
## Decisions |
LOCKED — plans MUST implement these exactly. Flag if contradicted. |
## Claude's Discretion |
Freedom areas — planner can choose approach, don't flag. |
## Deferred Ideas |
Out of scope — plans must NOT include these. Flag if present. |
If CONTEXT.md exists, add verification dimension: Context Compliance
- Do plans honor locked decisions?
- Are deferred ideas excluded?
- Are discretion areas handled appropriately? </upstream_input>
<core_principle> Plan completeness =/= Goal achievement — a task "create auth endpoint" can be in the plan while password hashing is missing; the task exists but goal "secure authentication" won't be achieved.
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 · 957 lines · 36 tokens per session scan A 414f1c00f4a3
gsd-plan-checker is an agent published in the GitHub repository buildomator/buildomator (86 stars, last pushed 3d ago), licensed MIT. It adds 36 tokens to every session and 8,513 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to gsd-plan-checker, differing in 64 lines, and is treated as a copy.
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