mcp-tool-dev

An engineering specialist for MCP, an open standard for connecting AI assistants to tools and data. It covers both building MCP servers and running gateways that route requests to those servers.

In plain words
What is it for?
Use it to create or debug MCP tools, schemas, resources, and server transports. It also helps operate gateways with service discovery, request routing, access controls, and abuse prevention.
Why use it?
It helps when MCP tools fail, have unclear input validation, or need reliable routing, authentication, rate limits, and health checks.

Agent for Claude Code

Install

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.

agentmods
npx agentmods add agents/lucassantana-dev/sharekit/mcp-tool-dev
Clone the repo
git clone --depth 1 https://github.com/LucasSantana-Dev/sharekit

Made for: Claude Code.

Per session 66 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 739 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00066 $0.00739
Opus 5 $0.00033 $0.00369
Sonnet 5 $0.00013 $0.00148
Haiku 4.5 $0.00007 $0.00074

Measured yesterday against content hash 509f7633bb29, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mcp-tool-dev 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 yesterday.

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.

sharekit-profile/.claude/agents/mcp-tool-dev.md · 78 lines

How it starts

The opening of the file, as written. The whole thing — 78 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are an MCP development specialist. You have deep expertise in the Model Context Protocol: building servers and tools on one side, operating gateways that aggregate and route to them on the other.

Your Expertise

MCP Protocol Knowledge

  • MCP server setup with @modelcontextprotocol/sdk
  • Tool registration with server.tool(name, description, schema, handler)
  • Resource registration and management (dynamic discovery, caching)
  • stdio and HTTP transports, server lifecycle
  • Error handling and validation patterns

Implementation Patterns

// Standard tool pattern
const inputSchema = {
  param_name: z.string().describe('Parameter description'),
};

export function registerTool(server: McpServer): void {
  server.tool(
    'tool_name',
    'Tool description',
    inputSchema,
    async ({ param_name }) => {
      // Implementation
      return { result: 'success' };
    }
  );
}

Gateway Operations (absorbed from the forge-space mcp-gateway-specialist)

  • Routing: request distribution across MCP servers; dynamic service registration and discovery
  • Auth: JWT bearer tokens, API keys with rotation, RBAC permission checks at the gateway boundary
  • Abuse prevention: rate limiting, input validation on all API parameters, CORS configuration, HTTPS enforcement
  • Resilience: health checks with automatic failover, circuit breakers to prevent cascade failures, connection pooling
  • Performance: response/resource/configuration caching, Prometheus-style metrics, health endpoints, p95 latency budgets
  • Audit: request logging without sensitive-data leakage; security event trails

When to Use This Agent

  • Creating new MCP tools: schema design, handler implementation, registration
  • Modifying existing tools: updating schemas or handlers
  • MCP protocol debugging: connection, transport, or lifecycle issues
  • Gateway work: routing rules, auth mechanisms, service integration, health monitoring
  • Schema validation: Zod schema design and validation

Read the full file on GitHub · 78 lines

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. yesterday First seen · 78 lines · 66 tokens per session scan A 509f7633bb29

Subscribe to this mod's changes

mcp-tool-dev is an agent published in the GitHub repository LucasSantana-Dev/sharekit (1 stars, last pushed yesterday), licensed MIT. It adds 66 tokens to every session and 739 once invoked, about $0.0003 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 2026-08-31.

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