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mcp-builder

Guide for creating high-quality MCP (Model Context Protocol) servers that enable LLMs to interact with external services through well-designed tools. Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK).

2.21x
Quality

82%

Does it follow best practices?

Impact

93%

2.21x

Average score across 10 eval scenarios

SecuritybySnyk

—

The risk profile of this skill

The canonical home for this skill is pleaseai/mcp-dev

SKILL.md
Quality
Evals
Security

Quality

Content

67%Weight 40%Scale 1-5

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

A well-structured orchestrating skill: a clear four-phase workflow with concrete commands, URLs, and validation checkpoints, deferring language-specific detail to clearly signaled reference guides. The main costs are token redundancy — the trailing 'Reference Files' section and parts of Phase 4 duplicate content already stated earlier — and the absence of explicit error-recovery loops in the build/test phase.

Suggestions

Collapse the trailing 'Reference Files' documentation library into the phase sections where each guide is first cited (or keep only the library and drop the inline citations), removing ~40 lines of duplicate links and summaries.

In Phase 4, either fully delegate to evaluation.md ('Load the Evaluation Guide and follow its process') or inline the requirements — currently both the process steps and the question requirements are stated twice in the body.

Add an explicit feedback loop in Phase 3, e.g. 'If the build or inspector run fails, fix the errors and re-run before moving to Phase 4', to make the validation checkpoints gated rather than implied.

DimensionReasoningScore

Conciseness

The four-phase process is mostly tight, but there is real redundancy and padding: the closing 'Reference Files' section (~40 lines) re-lists the same four guide links and SDK URLs already given in Phase 1, each with bullet summaries of their contents; Phase 4 says 'follow the process outlined in the evaluation guide' and then restates that process and requirements inline; and 'high-quality SDK support... AI models are good at generating TypeScript code, benefiting from its broad usage, static typing and good linting tools' is justification Claude does not need. This fits 'mostly efficient but includes some unnecessary explanation or could be tightened' rather than the minor-trim level of 4.

3 / 5

Actionability

Concrete, executable specifics are given throughout: exact URLs with the '.md' suffix fetch trick ('https://modelcontextprotocol.io/sitemap.xml', raw GitHub SDK READMEs), exact commands ('npm run build', 'npx @modelcontextprotocol/inspector', 'python -m py_compile your_server.py'), named libraries (Zod, Pydantic), the four annotation flags, and a filled-in XML qa_pair example. It is not 5 because the core Phase 2 implementation guidance is checklist-level ('API client with authentication', 'Error handling helpers') with no code in the body — the code is delegated to the reference guides — leaving minor gaps.

4 / 5

Workflow Clarity

The four phases (Deep Research and Planning → Implementation → Review and Test → Create Evaluations) are clearly sequenced with numbered subsections and validation checkpoints: 'Run npm run build to verify compilation', 'Verify syntax: python -m py_compile', 'Test with MCP Inspector', and 'Answer Verification: Solve each question yourself to verify answers'. It falls short of 5 because there is no explicit error-recovery loop (no 'if the build/validation fails, fix and re-run before proceeding'), so it matches 'clear sequence with most checkpoints present; minor validation gaps'. No destructive/batch-operation cap applies since evaluation questions are explicitly required to be read-only.

4 / 5

Progressive Disclosure

The body is an overview-plus-process that defers detail to one-level-deep, well-signaled references with load timing ('Load During Phase 1/2', 'Load During Phase 4') and descriptive summaries. It is not 5 for two organizational reasons: the same four references are linked twice (inlined in Phases 1-2 and again in the trailing 'Reference Files' library), and the referenced './reference/*.md' files are not present in the provided bundle (no references/ directory), so the links cannot be verified to resolve. This places it at 'good structure; most content appropriately placed; references mostly clear; minor organization gaps'.

4 / 5

Total

15

/

20

Passed

Description

90%Weight 40%Scale 1-5

Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.

A strong description: third-person, concrete about the domain, with an explicit 'Use when...' trigger clause covering both Python/FastMCP and Node/TypeScript stacks. The only weakness is that 'what' is stated at the level of one or two actions rather than an enumerated list of capabilities, and 'high-quality'/'well-designed' add mild puffery without information.

DimensionReasoningScore

Specificity

Names the domain clearly ('creating high-quality MCP (Model Context Protocol) servers') with 1-2 concrete actions ('enable LLMs to interact with external services through well-designed tools', 'integrate external APIs or services'), but does not enumerate several specific actions (e.g., designing tool schemas, implementing transports, testing) — matching the 'names domain and 1-2 concrete actions, but not comprehensive' anchor. 'High-quality' and 'well-designed' are mild filler that keep it below the 'lists several specific actions' level of 4.

3 / 5

Completeness

Explicitly answers both questions: what — 'Guide for creating high-quality MCP servers that enable LLMs to interact with external services through well-designed tools', and when — 'Use when building MCP servers to integrate external APIs or services, whether in Python (FastMCP) or Node/TypeScript (MCP SDK)'. This matches the top anchor: a concrete 'what' plus an explicit 'Use when...' clause with concrete trigger phrases. Voice is third person ('Guide for creating...'), so no person-voice penalty applies.

5 / 5

Trigger Term Quality

Comprehensive natural-term coverage for this domain: 'MCP', 'Model Context Protocol', 'MCP servers', 'building', 'external APIs or services', plus stack synonyms 'Python (FastMCP)', 'Node/TypeScript', 'MCP SDK' — a user asking for any of these would naturally phrase it in these terms. It is not score 4 because no commonly used variation of the request (MCP, Model Context Protocol, FastMCP, SDK, API integration) is missing.

5 / 5

Distinctiveness Conflict Risk

MCP server development is a clear niche with distinct triggers ('MCP servers', 'Model Context Protocol', 'FastMCP', 'MCP SDK'), so it would not fire for unrelated skills; overlap risk is limited to near-identical MCP tooling skills, which is minimal. It clearly exceeds the 'mostly distinct; minor overlap risk' anchor at 4.

5 / 5

Total

18

/

20

Passed

Validation

93%

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 15 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

relative_links

Relative link issues: 10 missing

Warning

Total

15

/

16

Passed

Repository

majiayu000/claude-skill-registry-data

Path

data/05-backend-mcpbuilder/SKILL.md

Reviewed

Table of Contents

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