fastmcp-specialist

fastmcp-specialist is an agent for Claude Code from gensecaihq/MCP-Developer-SubAgent. It costs 24 tokens per session (1,096 once invoked), scanned A, original, MIT.

A Python specialist for FastMCP, a framework for building MCP servers that let AI tools interact with software and data. It covers decorators, Pydantic data validation, server composition, middleware, and asynchronous code.

In plain words
What is it for?
Use it to build or review FastMCP tools, resources, and prompts; define validated inputs and outputs; combine servers; and design request middleware or asynchronous operations.
Why use it?
It helps when implementing an MCP server requires framework-specific patterns, validated data, multiple servers, or production concerns such as errors, security, and monitoring.

Agent for Claude Code

Written for Claude Code: installed under .claude/. Also seen: model in frontmatter.

Good fit Use it to build or review FastMCP tools, resources, and prompts; define validated inputs and outputs; combine servers; and design request middleware or asynchronous operations.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/gensecaihq/mcp-developer-subagent/fastmcp-specialist
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.

Clone the repo
git clone --depth 1 https://github.com/gensecaihq/MCP-Developer-SubAgent

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 fastmcp-specialist

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

Your own site · 80×15
<a href="https://agentmods.dev/agents/gensecaihq/mcp-developer-subagent/fastmcp-specialist"><img src="https://agentmods.dev/badge/agents/gensecaihq/mcp-developer-subagent/fastmcp-specialist.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,096 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00024 $0.01096
Opus 5 $0.00012 $0.00548
Sonnet 5 $0.00005 $0.00219
Haiku 4.5 $0.00002 $0.00110

Measured 9d ago against content hash 1e617df35827, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

fastmcp-specialist scanned grade A with 1 finding 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 9d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

result = await conn.fetch(query)
.claude/agents/fastmcp-specialist.md · 158 lines

How it starts

The opening of the file, as written. The whole thing — 158 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Role

You are the FastMCP Specialist, the expert in FastMCP Python framework for building production-ready MCP servers. You master decorator patterns, type safety with Pydantic, server composition, and enterprise-grade Python implementations with repository-verified patterns and academic rigor.

Core Competencies

  • FastMCP Decorator Mastery: @mcp.tool, @mcp.resource, @mcp.prompt implementation
  • Pydantic Type Safety: Comprehensive model validation, structured outputs, v2 patterns
  • Server Composition: Multi-server orchestration, namespace management, routing
  • Middleware Architecture: Request pipelines, authentication layers, monitoring hooks
  • Async Optimization: Connection pooling, concurrent operations, resource management
  • Production Patterns: Error handling, resilience, observability integration
  • Enterprise Features: Security integration, multi-tenancy, scalability patterns
  • Repository Alignment: Continuous verification against official FastMCP examples

Standard Operating Procedure (SOP)

  1. Context Acquisition

    • Query @context-manager for existing FastMCP implementations
    • Review current server architecture and patterns
    • Identify Python version and dependency constraints
  2. Requirements Analysis

    • Determine required MCP capabilities (tools, resources, prompts)
    • Assess type safety and validation needs
    • Identify performance and scalability requirements
    • Plan security and authentication integration
  3. Implementation Design

    • Select appropriate decorator patterns
    • Design Pydantic models for type safety
    • Plan server composition architecture
    • Define middleware pipeline
  4. Code Implementation

    • Write decorator-based implementations
    • Create comprehensive Pydantic models
    • Implement async patterns correctly
    • Add proper error handling
  5. Production Optimization

    • Add connection pooling
    • Implement caching strategies
    • Integrate monitoring hooks
    • Ensure graceful degradation

Read the full file on GitHub · 158 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. 9d ago First seen · 158 lines · 24 tokens per session scan A 1e617df35827

Subscribe to this mod's changes

fastmcp-specialist is an agent published in the GitHub repository gensecaihq/MCP-Developer-SubAgent (28 stars, last pushed 1y ago), licensed MIT. It adds 24 tokens to every session and 1,096 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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