Agent Tool-Use Stack (MCP)

\documentclass[border=6pt]{standalone}

% --- packages (mirror these in template.meta.json "requires") ---
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\usetikzlibrary{svg.path, positioning, arrows.meta}

% --- palette (canonical source: reference/color-palettes/color-palettes.md; light variant) ---
\definecolor{otblue}{HTML}{0072B2}
\definecolor{otorange}{HTML}{E69F00}
\definecolor{otteal}{HTML}{009E73}
\definecolor{otpurple}{HTML}{CC79A7}
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% --- brand colors (official; exception documented in icons/brands/README.md) ---
\definecolor{brandclaude}{HTML}{D97757}
\definecolor{brandmcp}{HTML}{000000}
\definecolor{brandgithub}{HTML}{181717}
\definecolor{brandarxiv}{HTML}{B31B1B}
\definecolor{brandgooglescholar}{HTML}{4285F4}

\begin{document}
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% ==== parameters (edit these) ============================================
\def\cardw{2.4}       % card width (cm)
\def\cardh{1.9}       % logo-card height (cm)
\def\toolgap{0.45}    % vertical gap between tool cards (cm)
% labels
\def\userlabel{User}
\def\llmlabel{Claude}
\def\mcplabel{MCP servers}
\def\toolalabel{GitHub}
\def\toolblabel{arXiv}
\def\toolclabel{Scholar}
\def\chatlabel{chat}
\def\calllabel{tool calls}
% =========================================================================

\begin{tikzpicture}[
    >={Stealth[length=2.4mm]},
    card/.style={
      draw=otgray!55, line width=0.7pt, rounded corners=4pt, align=center,
      minimum width=\cardw cm, minimum height=\cardh cm,
    },
    cardlabel/.style={font=\sffamily\small, text=otgray!40!black},
    flow/.style={draw=otgray!70, line width=0.9pt, ->},
    elabel/.style={font=\sffamily\footnotesize, text=otgray},
  ]

  % --- user ---
  \node[card, fill=otgray!10, minimum height=1.2cm] (user) at (0,0) {\sffamily\small \userlabel};

  % --- LLM core ---
  \node[card, fill=otorange!14, right=2.0cm of user] (llm) {};
  \pic[scale=0.3] at ([yshift=0.28cm]llm.center) {picclaude};
  \node[cardlabel] at ([yshift=-0.42cm]llm.center) {\llmlabel};

  % --- protocol layer ---
  \node[card, fill=otblue!12, right=2.0cm of llm] (mcp) {};
  \pic[scale=0.28] at ([yshift=0.28cm]mcp.center) {picmcp};
  \node[cardlabel] at ([yshift=-0.42cm]mcp.center) {\mcplabel};

  % --- tool cards (top -> bottom: t1, t2, t3) ---
  \node[card, fill=otteal!12, right=2.0cm of mcp, yshift=\cardh cm+\toolgap cm] (t1) {};
  \pic[scale=0.26] at ([yshift=0.26cm]t1.center) {picgithub};
  \node[cardlabel] at ([yshift=-0.42cm]t1.center) {\toolalabel};

  \node[card, fill=otteal!12, right=2.0cm of mcp] (t2) {};
  \pic[scale=0.26] at ([yshift=0.26cm]t2.center) {picarxiv};
  \node[cardlabel] at ([yshift=-0.42cm]t2.center) {\toolblabel};

  \node[card, fill=otteal!12, right=2.0cm of mcp, yshift=-\cardh cm-\toolgap cm] (t3) {};
  \pic[scale=0.26] at ([yshift=0.26cm]t3.center) {picgooglescholar};
  \node[cardlabel] at ([yshift=-0.42cm]t3.center) {\toolclabel};

  % --- flows ---
  \draw[flow, <->] (user) -- (llm) node[midway, above, elabel] {\chatlabel};
  \draw[flow, <->] (llm) -- (mcp) node[midway, above, elabel] {\calllabel};
  \draw[flow] (mcp.20) -- (t1.west);
  \draw[flow] (mcp.east) -- (t2.west);
  \draw[flow] (mcp.-20) -- (t3.west);

\end{tikzpicture}
\end{document}