Borrowing it
Nothing to install: this file belongs to mark3labs/mcphost. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/mark3labs/mcphost/main/AGENTS.mdgit clone --depth 1 https://github.com/mark3labs/mcphostWrote 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/instructions/mark3labs/mcphost/agents-md)<a href="https://agentmods.dev/instructions/mark3labs/mcphost/agents-md"><img src="https://agentmods.dev/badge/instructions/mark3labs/mcphost/agents-md/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.
<a href="https://agentmods.dev/instructions/mark3labs/mcphost/agents-md"><img src="https://agentmods.dev/badge/instructions/mark3labs/mcphost/agents-md.svg" alt="Reviewed on agentmods" width="80" 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 | $0.00380 | $0.00380 |
| Opus 5.5 | $0.00152 | $0.00152 |
| Sonnet 5.5 | $0.00076 | $0.00076 |
| Haiku 4.5 | $0.00038 | $0.00038 |
Grade A, and why
mcphost AGENTS.md 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.
What it actually says
OpenSpec Instructions
These instructions are for AI assistants working in this project.
Always open @/openspec/AGENTS.md when the request:
- Mentions planning or proposals (words like proposal, spec, change, plan)
- Introduces new capabilities, breaking changes, architecture shifts, or big performance/security work
- Sounds ambiguous and you need the authoritative spec before coding
Use @/openspec/AGENTS.md to learn:
- How to create and apply change proposals
- Spec format and conventions
- Project structure and guidelines
Keep this managed block so 'openspec update' can refresh the instructions.
MCPHost Agent Guidelines
Build/Test Commands
- Build:
go build -o output/mcphost - Test all:
go test -race ./... - Test single:
go test -race ./cmd -run TestScriptExecution - Lint:
go vet ./... - Format:
go fmt ./...
Code Style
- Imports: stdlib → third-party → local (blank lines between)
- Naming: camelCase (unexported), PascalCase (exported)
- Errors: Always check, wrap with
fmt.Errorf("context: %w", err) - Logging: Use
github.com/charmbracelet/logstructured logging - Types: Prefer
anyoverinterface{} - JSON: snake_case tags with
omitemptywhere appropriate - Context: First parameter for blocking operations
Architecture
- Multi-provider LLM support via
llm.Providerinterface - MCP client-server for tool integration
- Builtin servers: bash, fetch, todo, fs
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 · 41 lines · 380 tokens per session scan A 70c579aef2ea
mcphost AGENTS.md is an instructions file published in the GitHub repository mark3labs/mcphost (1,591 stars, last pushed 6mo ago), licensed MIT. It adds 380 tokens to every session, about $0.0015 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 2026-08-30.
mcphost AGENTS.md compared with instructions from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| mcphost AGENTS.mdmark3labs/mcphost | Instructions file | 1.6k | 6mo ago | MIT | A | 380 | Codex, OpenCode |
| vscode buildNext.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 9,719 | GitHub Copilot |
| next.js AGENTS.mdvercel/next.js | Instructions file | 143k | today | MIT | A | 7,461 | Codex, OpenCode |
| langchain AGENTS.mdlangchain-ai/langchain | Instructions file | 149k | yesterday | MIT | A | 4,680 | Codex, OpenCode |
| vscode oss-third-party-notices.instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 5,516 | GitHub Copilot |
| vscode copilot-instructions.mdmicrosoft/vscode | Instructions file | 195k | yesterday | MIT | A | 3,093 | GitHub Copilot |
| deepseek-harness AGENTS.mddeepseek-ai/deepseek-harness | Instructions file | 274k | 2d ago | MIT | A | 4,313 | Codex, OpenCode |