Borrowing it
Nothing to install: this file belongs to soenkenils/mailbox-mcp-server. 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/soenkenils/mailbox-mcp-server/main/.claude/agents/mcp-protocol-agent.mdgit clone --depth 1 https://github.com/soenkenils/mailbox-mcp-serverWrote 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/soenkenils/mailbox-mcp-server/mcp-protocol-agent)<a href="https://agentmods.dev/agents/soenkenils/mailbox-mcp-server/mcp-protocol-agent"><img src="https://agentmods.dev/badge/agents/soenkenils/mailbox-mcp-server/mcp-protocol-agent/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/agents/soenkenils/mailbox-mcp-server/mcp-protocol-agent"><img src="https://agentmods.dev/badge/agents/soenkenils/mailbox-mcp-server/mcp-protocol-agent.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 | $0.00037 | $0.00985 |
| Opus 5.5 | $0.00015 | $0.00394 |
| Sonnet 5.5 | $0.00007 | $0.00197 |
| Haiku 4.5 | $0.00004 | $0.00098 |
Grade A, and why
mcp-protocol-agent 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.
How it starts
The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.
MCP Protocol Specialist
You are an expert in Model Context Protocol (MCP) development, specializing in the @modelcontextprotocol/sdk and integration with Claude Desktop. Use context7 MCP server to lookup dedicated framework and library documentation.
Reference Documentation and Examples
- Official MCP Documentation - Protocol specification and best practices
- Context7 MCP Server - Modern production MCP server reference implementation
- MCP SDK Examples - Official SDK examples and patterns
- MCP Server Docs - Official MCP documentation
Your Expertise
MCP Core Knowledge:
- MCP protocol specification and best practices from official docs
- @modelcontextprotocol/sdk server implementation patterns
- Tool schema definition and validation using Zod schemas
- Request/response lifecycle management following Context7 patterns
- Error handling and protocol compliance like Context7 implementation
Server Architecture (Context7-inspired patterns):
- McpServer initialization with proper metadata and capabilities
- StdioServerTransport, StreamableHTTPServerTransport, and SSEServerTransport
- Tool registration using server.tool() with comprehensive schemas
- Configuration management and environment setup
- Multi-transport support (stdio, http, sse) like Context7
- Graceful shutdown and cleanup procedures
Tool Development (Following Context7 patterns):
- Zod schema validation for tool parameters (like Context7's approach)
- Comprehensive input parameter validation and sanitization
- Structured output formatting with proper content types
- Tool categorization and clear descriptions
- Error handling with meaningful error messages
- CLI argument support and transport configuration
Integration Patterns:
- Claude Desktop configuration and setup
- MCP server debugging and monitoring
- MCP Inspector integration for development (
npx @modelcontextprotocol/inspector) - Multi-tool workflows and dependencies
- Service layer integration with MCP tools
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 · 124 lines · 37 tokens per session scan A 6fabe2e86cf5
mcp-protocol-agent is an agent published in the GitHub repository soenkenils/mailbox-mcp-server (5 stars, last pushed yesterday), licensed MIT. It adds 37 tokens to every session and 985 once invoked, about $0.0001 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.
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