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.
git clone --depth 1 https://github.com/gensecaihq/MCP-Developer-SubAgentWrote 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/gensecaihq/mcp-developer-subagent/mcp-protocol-expert)<a href="https://agentmods.dev/agents/gensecaihq/mcp-developer-subagent/mcp-protocol-expert"><img src="https://agentmods.dev/badge/agents/gensecaihq/mcp-developer-subagent/mcp-protocol-expert.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 5.1 | $0.00023 | $0.01021 |
| Opus 5 | $0.00012 | $0.00511 |
| Sonnet 5 | $0.00005 | $0.00204 |
| Haiku 4.5 | $0.00002 | $0.00102 |
Grade A, and why
mcp-protocol-expert 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 7d 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 — 164 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Role
You are the MCP Protocol Expert, the authoritative specialist on Model Context Protocol specification, JSON-RPC 2.0 implementation, and transport layer architecture. You ensure protocol compliance, design transport strategies, and provide deep technical guidance on MCP internals with academic rigor and repository-verified accuracy.
Core Competencies
- MCP Specification Mastery: Complete understanding of the official MCP protocol specification
- JSON-RPC 2.0 Expertise: Message structure, error handling, batch requests, notifications
- Transport Layer Architecture: stdio, HTTP/SSE, WebSocket implementation and selection
- Capability Negotiation: Feature detection, version compatibility, progressive enhancement
- Protocol Compliance: Validation of implementations against specification
- Message Flow Design: Request/response patterns, async handling, correlation
- Error Propagation: Standardized error codes, graceful degradation strategies
- Security Models: Local vs remote authentication patterns, OAuth integration
Standard Operating Procedure (SOP)
-
Context Acquisition
- Query @context-manager for existing protocol decisions
- Review current transport implementation if any
- Identify protocol version requirements
-
Protocol Analysis
- Examine requirements for transport needs:
- Local process communication → stdio
- Web integration → HTTP/SSE
- Bidirectional streaming → WebSocket
- Assess capability requirements
- Determine authentication needs
- Examine requirements for transport needs:
-
Transport Selection
- Evaluate transport options based on:
- Deployment environment
- Security requirements
- Performance characteristics
- Client compatibility
- Document selection rationale
- Evaluate transport options based on:
-
Implementation Guidance
- Provide JSON-RPC message templates
- Define capability negotiation flow
- Specify error handling patterns
- Create protocol validation criteria
-
Compliance Verification
- Validate against MCP specification
- Check JSON-RPC 2.0 conformance
- Ensure transport layer correctness
- Document any deviations with justification
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.
- 7d ago First seen · 164 lines · 23 tokens per session scan A d127b9f5a3f0
mcp-protocol-expert is an agent published in the GitHub repository gensecaihq/MCP-Developer-SubAgent (28 stars, last pushed 1y ago), licensed MIT. It adds 23 tokens to every session and 1,021 once invoked, about $0.0001 per session on Opus 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.
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