What is agent-friendly-mcp?

Guidelines for designing and reviewing MCP servers, which are services that coding agents call for tools or data. They focus on making those tools easy to find, understand, invoke, and recover from when something goes wrong.

Building or auditing MCP server discovery, tool descriptions, input schemas, error handling, and other agent-facing behavior.

They reduce wrong tool choices, unnecessary token use, and repeated invalid calls caused by unclear tool names or input rules.

How briandconnelly/moonbridge configures Claude Code

Reuse

Borrowing it

Nothing to install: this file belongs to briandconnelly/moonbridge. 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/briandconnelly/moonbridge/main/.agents/skills/agent-friendly-mcp/SKILL.md

Clone the repo

git clone --depth 1 https://github.com/briandconnelly/moonbridge

Made for: Claude Code.

Or install moonbridge, the plugin that ships this one along with the rest of its 5 skills, 1 MCP server.

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/briandconnelly/moonbridge/agent-friendly-mcp/github.svg)](https://agentmods.dev/skills/briandconnelly/moonbridge/agent-friendly-mcp)

Your own site

<a href="https://agentmods.dev/skills/briandconnelly/moonbridge/agent-friendly-mcp"><img src="https://agentmods.dev/badge/skills/briandconnelly/moonbridge/agent-friendly-mcp/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/briandconnelly/moonbridge/agent-friendly-mcp"><img src="https://agentmods.dev/badge/skills/briandconnelly/moonbridge/agent-friendly-mcp.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 130 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,076 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 91% copy Near-identical to another mod 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	$0.00130	$0.03076
Opus 5	$0.00065	$0.01538
Sonnet 5	$0.00026	$0.00615
Haiku 4.5	$0.00013	$0.00308

Measured 9d ago against content hash 59e665acbed9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

agent-friendly-mcp 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.

The scan reads SKILL.md. This mod also ships 5 executable files (tests/check_rule_ids.py, tests/check_stale_terms.py, tests/test_check_rule_ids.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Origin

This is a copy

91% identical to agent-friendly-mcp — 29 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/agent-friendly-mcp/SKILL.md · 124 lines

How it starts

The opening of the file, as written. The whole thing — 124 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Agent-Friendly MCP

Use this skill to make MCP servers easy for agents to discover, invoke correctly, recover from, and use at low token cost without sacrificing correctness.

Spec Baseline

This skill is written against the MCP 2026-07-28 specification (final, released 2026-07-28); the field names, capability paths, method set, and task lifecycle it uses follow that revision, including the io.modelcontextprotocol/tasks extension (SEP-2663). Status caveat: the 2026-07-28 changelog calls tasks an official extension while the ext-tasks specification repository still labels itself experimental — treat the task contract as extension-versioned and re-verify it against the extension spec when it cuts a release. The protocol core is stateless: there is no initialize handshake or session id — every request carries io.modelcontextprotocol/protocolVersion and io.modelcontextprotocol/clientCapabilities in _meta (both required), and servers advertise their own capabilities via the mandatory server/discover method. Server-initiated requests are gone: elicitation, sampling, and roots requests ride Multi Round-Trip Requests (resultType: "input_required" with inputRequests, answered by retrying with inputResponses), and push notifications ride an opt-in subscriptions/listen stream. Every result carries a required resultType, and list/read results carry the native cache hints ttlMs and cacheScope. Roots, sampling, logging, the HTTP+SSE transport, and Dynamic Client Registration are deprecated on a twelve-month minimum window; design new servers without them. The extensions framework is formal but demanding: an extension needs a reverse-DNS identifier, its own maintained specification, and negotiation by both peers (declared in clientCapabilities.extensions and server/discover), so a namespaced _meta key remains a private convention until someone does that work. This section is the single home for spec-revision facts; other files cite it rather than restating them. For clients that still speak 2025-11-25, the binding rules here still govern what you build; the old revision's wire differences and version-bound failure modes are cataloged in the informative mcp-2025-11-25-compat.md, and decisions/001-mcp-2026-07-28-rebase.md records the rebase decision, verified fact sheet, and impact matrix.

Read the full file on GitHub · 124 lines

Files

What ships with it

42 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 124 lines · 130 tokens per session scan A 59e665acbed9

Subscribe to this mod's changes

agent-friendly-mcp is a skill published in the GitHub repository briandconnelly/moonbridge (0 stars, last pushed today), licensed MIT. It adds 130 tokens to every session and 3,076 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to agent-friendly-mcp, differing in 29 lines, and is treated as a copy.

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