How do I install the Debug MCP Agent skill?

Run npx skillmds@latest add sailingnaturali/debug-mcp-agent in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Debug MCP Agent safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Debug MCP Agent?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Debug MCP Agent free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Debug MCP Agent?

sailingnaturali (@sailingnaturali) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Debug MCP Agent by sailingnaturali — Agent Skill

Name: Debug MCP Agent
Author: sailingnaturali

Debug MCP Agent

Use when an AI agent backed by MCP servers or tools misbehaves — claims data is missing/unavailable, returns 404s or "server unreachable", gives plausible-but-wrong answers, queries the wrong path, or leaks chain-of-thought / control tokens. Probe ground truth before trusting the agent's account of itself.

File contents

Debug an MCP / tool-backed agent

The agent's own narration of what went wrong is often the bug. Probe ground truth directly, out of band, before trusting anything the agent said.

1. Ground truth — query the source directly, bypass the agent

Hit the underlying API / DB / tool yourself (curl, the CLI, a direct query) for the exact thing the agent claimed was missing.

Data is there → the failure is in the MCP/tool/agent layer, not the source.
Genuinely absent (404 / empty) → that's "not available," not an error. Agents and MCP clients routinely conflate the two; a burst of 404s can even trip a client's circuit breaker and swallow valid reads afterward.
Connection refused / unreachable → the source or the MCP process is down — not a missing field. Confirm the process/container is up; restart it.

2. Which model is driving?

Confirm the configured model is the one you expect. A weaker or local model silently swapped in is a common root cause of: leaked chain-of-thought, leaked control tokens, skipped tool calls, replies truncated mid-sentence, and confident confabulation about things it can't see.

3. The tool / MCP layer

"MCP server X unreachable after N attempts" = the MCP process or its backing service died mid-conversation — not a missing path. Different fix than "data absent."
Wrong path / argument guessed (e.g. sensors.depth vs the real environment.depth.belowTransducer): the agent is inventing the schema. Ground the real shape in the prompt, or give it a list/describe tool so it stops guessing identifiers.
Auth, not absence: a 401/403 on a write or a privileged/admin route is a permissions problem, not missing data — check the token's scope, not the data.

4. Plausible-but-wrong values

If the numbers look reasonable but are wrong, suspect a mock / fixture / sandbox data source rather than a logic bug — confirm which environment the agent is actually pointed at.

Close out

A new root cause is a reusable lesson — write it into a lessons doc or runbook so the next person doesn't re-derive it. The single highest-leverage habit when an agent misbehaves: never trust its self-report; reproduce against ground truth first.

---name: debug-mcp-agentdescription: Use when an AI agent backed by MCP servers or tools misbehaves — claims data is missing/unavailable, returns 404s or "server unreachable", gives plausible-but-wrong answers, queries the wrong path, or leaks chain-of-thought / control tokens. Probe ground truth before trusting the agent's account of itself.---# Debug an MCP / tool-backed agentThe agent's own narration of what went wrong is often *the bug*. **Probe ground truthdirectly, out of band, before trusting anything the agent said.**## 1. Ground truth — query the source directly, bypass the agentHit the underlying API / DB / tool yourself (curl, the CLI, a direct query) for the exactthing the agent claimed was missing.- **Data is there** → the failure is in the MCP/tool/agent layer, not the source.- **Genuinely absent (404 / empty)** → that's "not available," **not an error**. Agents and MCP clients routinely conflate the two; a burst of 404s can even trip a client's circuit breaker and swallow *valid* reads afterward.- **Connection refused / unreachable** → the source or the MCP process is down — not a missing field. Confirm the process/container is up; restart it.## 2. Which model is driving?Confirm the configured model is the one you expect. A weaker or local model silently swappedin is a common root cause of: leaked chain-of-thought, leaked control tokens, skipped toolcalls, replies truncated mid-sentence, and confident confabulation about things it can't see.## 3. The tool / MCP layer- **"MCP server X unreachable after N attempts"** = the MCP process or its backing service died mid-conversation — *not* a missing path. Different fix than "data absent."- **Wrong path / argument guessed** (e.g. `sensors.depth` vs the real `environment.depth.belowTransducer`): the agent is inventing the schema. Ground the real shape in the prompt, or give it a list/describe tool so it stops guessing identifiers.- **Auth, not absence:** a `401/403` on a write or a privileged/admin route is a permissions problem, not missing data — check the token's scope, not the data.## 4. Plausible-but-wrong valuesIf the numbers look reasonable but are wrong, suspect a **mock / fixture / sandbox** datasource rather than a logic bug — confirm which environment the agent is actually pointed at.## Close outA new root cause is a reusable lesson — write it into a lessons doc or runbook so the nextperson doesn't re-derive it. The single highest-leverage habit when an agent misbehaves:**never trust its self-report; reproduce against ground truth first.**

Frequently asked questions