A troubleshooting guide for Gantry's MCP proxy, the layer that passes tool requests between an agent and the server. It covers logs, request history, sessions, caches, safety checks, retries, and circuit breakers.

Debugging failed or delayed tool calls, stale cached data, false safety warnings, retry storms, circuit-breaker trips, and proxy instability.

It provides a structured way to investigate unexpected tool results or stuck agents before changing code, and helps identify shared state or server-health problems.

How geleynse/gantry configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to geleynse/gantry. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/geleynse/gantry/main/.claude/skills/debug-proxy/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/geleynse/gantry

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/geleynse/gantry/debug-proxy/github.svg)](https://agentmods.dev/skills/geleynse/gantry/debug-proxy)

Your own site

<a href="https://agentmods.dev/skills/geleynse/gantry/debug-proxy"><img src="https://agentmods.dev/badge/skills/geleynse/gantry/debug-proxy/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/geleynse/gantry/debug-proxy"><img src="https://agentmods.dev/badge/skills/geleynse/gantry/debug-proxy.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 49 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,612 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

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.

Model	Per session	Once invoked
Fable 5.1	$0.00049	$0.02612
Opus 5.5	$0.00020	$0.01045
Sonnet 5.5	$0.00010	$0.00522
Haiku 4.5	$0.00005	$0.00261

Measured 2mo ago against content hash 1b32f27e5bd4, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

debug-proxy 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 2mo 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.

.claude/skills/debug-proxy/SKILL.md · 193 lines

How it starts

The opening of the file, as written. The whole thing — 193 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugging the Proxy — Gantry

Systematic approach for "an agent got a weird result" or "an agent is stuck" reports. Work top-down: logs → tool-call history → session state → server health, before touching guard/injection code.

1. Turn up logging

LOG_LEVEL=debug bun run dev      # or set in the environment before `bun dist/index.js`

Format (from src/lib/logger.ts, createLogger(category)):

[2026-07-01T12:34:56.789Z] [DEBUG] [passthrough] jump BEFORE | agent: rust-vane, system: sol_prime, dest: void_reach, fuel: 42, tick: 118, server_tick: 119, drift: 1

[LEVEL] [category] message | key: value, key2: value2. Useful categories to grep for: pipeline, passthrough, registry, gantry-v2, compound-tools, fuel-floor-guard, circuit-breaker, session, instability-hints, instability-metrics, proxy (constants/reformat). console.error is used for WARN/ERROR, console.log for INFO/DEBUG — pipe accordingly if you're filtering stdout vs stderr.

2. Read the tool-call history — two-phase pending→complete records

Every tool call writes a row to the proxy_tool_calls SQLite table ($FLEET_DIR/data/fleet.db) via tool-call-logger.ts:

logToolCallStart(agent, toolName, args, opts) inserts a row with status = "pending" and returns a numeric pendingId.
logToolCallComplete(pendingId, agent, toolName, result, durationMs, opts) updates that same row to status = "complete" or "error", filling in result_summary, duration_ms, success, error_code.

Columns worth querying directly: agent, tool_name, args_summary, result_summary, success, error_code, duration_ms, is_compound, status, trace_id, parent_id (compound tools log sub-calls with parent_id pointing at the parent row — same mechanism PrayerLang uses to build its execution tree), timestamp.

A row stuck at status = "pending" with no matching complete update means the call never returned — either it's still in flight, or the process crashed/restarted mid-call (the pendingId insert survives; nothing ever calls logToolCallComplete for it). That's a strong signal to check for a server restart or an unhandled exception around that timestamp.

Read the full file on GitHub · 193 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.

2mo ago First seen · 193 lines · 49 tokens per session scan A 1b32f27e5bd4

Subscribe to this mod's changes

debug-proxy is a skill published in the GitHub repository geleynse/gantry (4 stars, last pushed 2mo ago), licensed MIT. It adds 49 tokens to every session and 2,612 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.

Debugging

debug-proxy next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
debug-proxygeleynse/gantry	Skill	4	2mo ago	MIT	A	49	Claude Code
systematic-debuggingopen-metadata/OpenMetadata	Skill	16k	yesterday	Apache-2.0	A	37	Claude Code
log-error-digestzebbern/claude-code-guide	Skill	4.7k	3d ago	MIT	A	71	Claude Code, Codex
cwv-optimizeradobe/skills	Skill	319	yesterday	Apache-2.0	A	112	Claude Code
ci-fixersipyourdrink-ltd/bernstein	Skill	1.2k	yesterday	Apache-2.0	A	15	Claude Code, Codex
incident-response-incident-responsermyndharis/antigravity-skills	Skill	1.9k	23d ago	MIT	A	36	Claude Code
triaging-web-analytics-supportPostHog/posthog	Skill	41k	yesterday	none	A	151	Claude Code, Codex

gantry: Skill for Claude Code