What is mcp-tool-change?

A checklist for adding, renaming, or removing an MCP tool in the GenCC-Link codebase. It covers the tool module, registration, the official capabilities list, tests, and documentation.

Use it when changing GenCC-Link's MCP tools, including gene, disease, assertion, discovery, or submitter tools, and when updating their tests and connection guides.

It prevents a tool change from being added in one place while missing another part of the public tool inventory.

How berntpopp/gencc-link configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to berntpopp/gencc-link. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file

curl -O https://raw.githubusercontent.com/berntpopp/gencc-link/main/.claude/skills/mcp-tool-change/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/berntpopp/gencc-link

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/berntpopp/gencc-link/mcp-tool-change/github.svg)](https://agentmods.dev/skills/berntpopp/gencc-link/mcp-tool-change)

Your own site

<a href="https://agentmods.dev/skills/berntpopp/gencc-link/mcp-tool-change"><img src="https://agentmods.dev/badge/skills/berntpopp/gencc-link/mcp-tool-change/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/berntpopp/gencc-link/mcp-tool-change"><img src="https://agentmods.dev/badge/skills/berntpopp/gencc-link/mcp-tool-change.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 48 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 749 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. 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.

Model	Per session	Once invoked
Fable 5.1	$0.00048	$0.00749
Opus 5	$0.00024	$0.00375
Sonnet 5	$0.00010	$0.00150
Haiku 4.5	$0.00005	$0.00075

Measured 9d ago against content hash 808cbdaee251, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

mcp-tool-change 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 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.

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.

.claude/skills/mcp-tool-change/SKILL.md · 59 lines

How it starts

The opening of the file, as written. The whole thing — 59 lines — stays where its author put it; the contents beside it link to each section on GitHub.

MCP tool change

Use this skill when changing the MCP tool surface (additions, renames, removals, description rewrites). GenCC-Link exposes exactly 10 tools today; the tool list is part of the public contract.

Checklist

Pick the tool module. Tools are grouped by concern under gencc_link/mcp/tools/:
- discovery: discovery.py (get_server_capabilities, get_gencc_diagnostics)
- genes: genes.py (search_genes, get_gene_curations)
- diseases: diseases.py (search_diseases, get_disease_curations)
- assertions: assertions.py (get_gene_disease_assertion, find_curations, resolve_identifier)
- submitters: submitters.py (list_submitters) Add the tool to the matching register_*_tools(mcp) function (create a new group only if it genuinely does not fit an existing one).
Register in the facade. If you added a new register_*_tools group, wire it into gencc_link/mcp/facade.py create_gencc_mcp().
Update the capabilities TOOLS tuple. Edit gencc_link/mcp/capabilities.py — the TOOLS tuple is the canonical inventory returned by get_server_capabilities and the gencc://capabilities resource. Order matters; keep it consistent with the README table.
Tune the description and envelope. Write the tool description for an AI client choosing a tool: what it does, when to use it, input/output shape, and what it does NOT do. Keep READ_ONLY_OPEN_WORLD annotations (gencc_link/mcp/annotations.py), the run_mcp_tool envelope (gencc_link/mcp/envelope.py), response_mode shaping (gencc_link/services/shaping.py), and _meta.next_commands (gencc_link/mcp/next_commands.py).
Error mapping. If the tool can raise a new exception, ensure it maps to a typed error code (invalid_input, not_found, ambiguous_query, data_unavailable, upstream_unavailable, rate_limited, internal_error) in gencc_link/exceptions.py / the envelope classifier.

Read the full file on GitHub · 59 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.

9d ago First seen · 59 lines · 48 tokens per session scan A 808cbdaee251

Subscribe to this mod's changes

mcp-tool-change is a skill published in the GitHub repository berntpopp/gencc-link (0 stars, last pushed 6d ago), licensed MIT. It adds 48 tokens to every session and 749 once invoked, about $0.0002 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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gencc-link: Skill for Claude Code