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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).

82

2.55x
Quality

75%

Does it follow best practices?

Impact

97%

2.55x

Average score across 3 eval scenarios

SecuritybySnyk

Low

Low-risk findings worth noting

Fix and improve this skill with Tessl

tessl review fix ./plugins/all-skills/skills/mcp-builder/SKILL.md
SKILL.md
Quality
Evals
Security

Quality

Content

63%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, actionable four-phase guide with concrete commands and clear sequencing, weakened by redundant reference listings and a bundle mismatch where the cited ./reference/ files are absent and the existing ./scripts/ files are not linked.

Suggestions

Create the referenced ./reference/ files (mcp_best_practices.md, python_mcp_server.md, node_mcp_server.md, evaluation.md) or repoint links to the actual ./scripts/ bundle so no reference is dangling.

Consolidate the reference-library listings into a single 'Reference Files' section to remove the triple repetition across phases 1.4, 2.4, and the final section.

Add one small inline code example (e.g., a minimal @mcp.tool registration with a Pydantic model) so the core implementation step is executable without loading a reference file.

DimensionReasoningScore

Conciseness

Mostly efficient and avoids explaining basics Claude knows, but the reference-file library is described three times (sections 1.4, 2.4, and the final 'Reference Files' section) and the bullet-heavy phases could be tightened, placing it at 'mostly efficient with some unnecessary repetition' rather than lean.

3 / 5

Actionability

Provides concrete executable commands (python -m py_compile, timeout 5s python server.py, npm run build), specific WebFetch URLs, a complete XML example, and exact tool-annotation flags; the main gap is that core tool-implementation code examples are delegated to reference files rather than shown inline.

4 / 5

Workflow Clarity

A clearly sequenced four-phase workflow with review/test checkpoints (3.1 Code Quality Review, 3.2 Test and Build with explicit hang-prevention guidance, 3.3 Quality Checklist) and an answer-verification loop in 4.2; minor validation gaps keep it just below a 5.

4 / 5

Progressive Disclosure

The design is good—clear overview with one-level-deep, well-signaled reference links—but the referenced ./reference/*.md files do not exist in the bundle, while the actual ./scripts/ bundle (evaluation.py, connections.py) is never linked from the body, and the reference library is redundantly listed three times; the broken/dangling references and mismatch with the real bundle exceed a 'minor organization gap'.

3 / 5

Total

14

/

20

Passed

Description

87%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, third-person description that clearly states both the capability and an explicit 'Use when' trigger with concrete, language-specific terms. It is comprehensive and distinctive with only minor keyword-coverage gaps.

DimensionReasoningScore

Specificity

Names the domain ("creating high-quality MCP servers") and several concrete actions—enabling LLMs to interact with external services, integrating external APIs/services, with language variants—noted as several specific actions with minor gaps rather than the fully comprehensive multi-action list of a 5.

4 / 5

Completeness

Explicitly answers both 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..."), with concrete trigger phrases.

5 / 5

Trigger Term Quality

Includes natural phrases users would say ("building MCP servers", "integrate external APIs or services") plus language-specific terms (FastMCP, Node/TypeScript, MCP SDK); a few common variations are missing, so not a 5.

4 / 5

Distinctiveness Conflict Risk

Clear niche (MCP server development) with distinct triggers (MCP servers, FastMCP, MCP SDK) and minimal overlap risk with unrelated skills.

5 / 5

Total

18

/

20

Passed

Validation

87%

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

Validation14 / 16 Passed

Validation for skill structure

CriteriaDescriptionResult

frontmatter_unknown_keys

Unknown frontmatter key(s) found; consider removing or moving to metadata

Warning

relative_links

Relative link issues: 14 missing

Warning

Total

14

/

16

Passed

Repository
davepoon/buildwithclaude
Reviewed

Table of Contents

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