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exocortex: Agent for Claude Code

.claude/agents/mcp-developer.md

MCP Developer is an agent for Claude Code from shawnhack/exocortex. It costs 3 tokens per session (215 once invoked), scanned A, original, MIT.

A coding guide for building and maintaining an MCP server. MCP is a standard way for an AI assistant to call tools and use outside data.

In plain words
What is it for?
Use it when working on MCP tools, memory operations, session-start context loading, server API routes, or tool descriptions that help an AI choose the right tool.
Why use it?
It keeps tool inputs, outputs, descriptions, stored knowledge, and session startup behavior consistent. It also makes changes safer by requiring coordination when tool interfaces change.

Agent for Claude Code

Written for Claude Code: SessionStart hook event. Also seen: model in frontmatter.

This is shawnhack/exocortex's own configuration. It tells Claude Code how to work on exocortex itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything exocortex configures →

not rated 1repo 1mo ago A scan 3 tokens original MIT
View source ↗ shawnhack/exocortex
Reuse

Borrowing it

Nothing to install: this file belongs to shawnhack/exocortex. 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/shawnhack/exocortex/main/.claude/agents/mcp-developer.md
Clone the repo
git clone --depth 1 https://github.com/shawnhack/exocortex

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.

agentmods badge for MCP Developer

README.md
[![agentmods](https://agentmods.dev/badge/agents/shawnhack/exocortex/mcp-developer/github.svg)](https://agentmods.dev/agents/shawnhack/exocortex/mcp-developer)
Your own site
<a href="https://agentmods.dev/agents/shawnhack/exocortex/mcp-developer"><img src="https://agentmods.dev/badge/agents/shawnhack/exocortex/mcp-developer/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.

agentmods 80×15 button for MCP Developer

Your own site · 80×15
<a href="https://agentmods.dev/agents/shawnhack/exocortex/mcp-developer"><img src="https://agentmods.dev/badge/agents/shawnhack/exocortex/mcp-developer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 3 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 215 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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00003 $0.00215
Opus 5.5 $0.00001 $0.00086
Sonnet 5.5 $0.00001 $0.00043
Haiku 4.5 $0.00000 $0.00021

Measured 2mo ago against content hash a0bdd09ce7f5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

MCP Developer 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/agents/mcp-developer.md · 30 lines

What it actually says

MCP Developer

Core Responsibilities

  • MCP server tools (memory_store, memory_search, memory_update, etc.)
  • Session-orient hook (session start context loading)
  • Server API routes
  • Tool description optimization for LLM trigger accuracy

Key Files

  • packages/mcp/src/ — MCP server implementation
  • packages/mcp/src/hooks/session-orient.js — SessionStart hook
  • packages/server/src/routes/ — REST API routes

Coding Constraints

  • Tool descriptions are prompt engineering — optimize for trigger accuracy
  • Validate all parameters before processing
  • Return structured JSON, not prose
  • Include attribution fields (provider, model_id, model_name, agent) on store operations
  • MCP tools accept tier parameter for knowledge tier scoping
  • Session-orient hook must complete within 3s timeout

Escalation

  • New MCP tools: discuss naming and description with user
  • Breaking changes to tool signatures: coordinate with all consumers
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.

  1. 2mo ago First seen · 30 lines · 3 tokens per session scan A a0bdd09ce7f5

Subscribe to this mod's changes

MCP Developer is an agent published in the GitHub repository shawnhack/exocortex (1 stars, last pushed 1mo ago), licensed MIT. It adds 3 tokens to every session and 215 once invoked, about $0.0000 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.

Backend and APIsBuilding agentsMemory and contextclaudeembeddingslocal-firstmcpmodel-context-protocol
Related

MCP Developer compared with agents from other repositories

MCP Developer next to 6 agents from other repositories
ModTypeStarsLast pushLicenceScanTokensWorks with
MCP Developershawnhack/exocortexAgent11mo agoMITA3Claude Code
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api-mappercogniplex/codememAgent183mo agoApache-2.0A50Claude Code
memory-curatorkostya-pakhomov/graphmindAgent23mo agoMITA45Claude Code
playwright-test-generatormicrosoft/playwrightAgent99kyesterdayApache-2.0A151Claude Code
.NET-Notebook-Migration-Agentmicrosoft/ai-agents-for-beginnersAgent79k4d agoMITA33Claude Code
code-revieweranthropics/claude-cookbooksAgent54k2d agoMITA52Claude Code