MCP tool conversion

Convert Model Context Protocol tool definitions into the OpenAI-compatible shape the chat API expects. No Client required — these are pure utilities in mcp.go.

mcpTool := openrouter.MCPTool{
    Name:        "get_weather",
    Description: "Get current weather",
    InputSchema: openrouter.MCPInputSchema{
        Type: "object",
        Properties: map[string]any{
            "location": map[string]any{"type": "string"},
        },
        Required: []string{"location"},
    },
}

tool := openrouter.ConvertMCPTool(mcpTool)

resp, _ := client.ChatComplete(ctx, messages,
    openrouter.WithModel("openai/gpt-4o"),
    openrouter.WithTools(tool),
)

See examples/mcp-tools/main.go.