Add Folklore variant evidence skill

[vladimir-mitev]

Summary

Adds a focused Agent Skill for retrieving and reviewing source-linked public
variant evidence and literature through Folklore Clinical Variant Interpretation
MCP, published by Helena Bioinformatics.

The skill is intentionally distinct from the existing database-lookup and
genomic-coordinates skills. It covers one public GRCh38 germline SNV or simple
indel through a structured live evidence contract, preserves six explicit
resolution states, stops on ambiguity, and chains only resolved variants into
source-linked literature review.

Type of change

• New skill
• Update to an existing skill
• Tests
• Repository tooling or CI
• Documentation
• Other:

Skills touched

• folklore-variant-evidence

How this was tested

uv run skills-ref validate ./skills/folklore-variant-evidence
Valid skill: skills/folklore-variant-evidence

uv run --with pytest python -m pytest tests/_meta -q
10 passed, 1214 subtests passed

skill-scanner scan ./skills/folklore-variant-evidence --use-behavioral
Status: SAFE; Max Severity: SAFE; Total Findings: 0

The public endpoint was also checked directly:

• tools/list returned search_variant_evidence,
  search_variant_literature, get_publication_details, and
  search_literature_corpus.
• The documented rs80357914 smoke test returned ambiguous with two
  candidates, confirming the skill's stop-and-select control flow.
• All official public documentation links returned HTTP 200. The MCP endpoint
  was verified by POST using the documented public protocol contract.

Related issues and references

• Public adapter and contract:
  https://github.com/helena-bioinformatics/folklore-mcp
• Integration setup: https://folklore.helena.bio/integrations
• Technical guide: https://folklore.helena.bio/docs/folklore-connector
• Official MCP Registry identity:
  io.github.helena-bioinformatics/folklore

Checklist

Skill format

• The skill directory name and the name frontmatter match exactly.
• The skill directory contains only SKILL.md and references/.
• SKILL.md has valid YAML frontmatter and a Markdown body.
• Only specification-defined top-level fields are present.
• metadata is a block mapping and scalar values are quoted where needed.
• No metadata.openclaw or metadata.hermes block is used.
• metadata.version exists and is quoted.
• The description says what the skill does and when an agent should use it.

Validation and tests

• skills-ref validate passes.
• No scripts are shipped, so a skill-specific suite and requirements entry
  are not required.
• Repository meta-tests pass.
• The security scanner reports SAFE with zero findings.

Content and safety

• The live public smoke test was executed.
• No secrets, credentials, private data, or unsafe instructions are
  included.
• No credentials are required.
• Relevant official public documentation is linked.

Notes for reviewers

Folklore Clinical Variant Interpretation MCP accepts public variant-level
queries only. It does not accept patient, phenotype, family, segregation, or
private case data. Results require qualified professional review and are not a
diagnosis or treatment recommendation. The skill explicitly directs broad
direct-database lookup and coordinate normalization tasks to the repository's
existing skills to avoid duplicating their scope.